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Sample records for acquired functional magnetic

  1. Corticomotoneuronal function and hyperexcitability in acquired neuromyotonia.

    PubMed

    Vucic, Steve; Cheah, Benjamin C; Yiannikas, Con; Vincent, Angela; Kiernan, Matthew C

    2010-09-01

    Acquired neuromyotonia encompasses a group of inflammatory disorders characterized by symptoms reflecting peripheral nerve hyperexcitability, which may be clinically confused in the early stages with amyotrophic lateral sclerosis. Despite a clear peripheral nerve focus, it remains unclear whether the ectopic activity in acquired neuromyotonia receives a central contribution. To clarify whether cortical hyperexcitability contributes to development of clinical features of acquired neuromyotonia, the present study investigated whether threshold tracking transcranial magnetic stimulation could detect cortical hyperexcitability in acquired neuromyotonia, and whether this technique could differentiate acquired neuromyotonia from amyotrophic lateral sclerosis. Cortical excitability studies were undertaken in 18 patients with acquired neuromyotonia and 104 patients with amyotrophic lateral sclerosis, with results compared to 62 normal controls. Short-interval intracortical inhibition in patients with acquired neuromyotonia was significantly different when compared to patients with amyotrophic lateral sclerosis (averaged short interval intracortical inhibition acquired neuromyotonia 11.3 +/- 1.9%; amyotrophic lateral sclerosis 2.6 +/- 0.9%, P < 0.001). In addition, the motor evoked potential amplitudes (acquired neuromyotonia 21.0 +/- 3.1%; amyotrophic lateral sclerosis 38.1 +/- 2.2%, P < 0.0001), intracortical facilitation (acquired neuromyotonia -0.9 +/- 1.3%; amyotrophic lateral sclerosis -2.3 +/- 0.6%, P < 0.0001), resting motor thresholds (acquired neuromyotonia 62.2 +/- 1.6%; amyotrophic lateral sclerosis 57.2 +/- 0.9%, P < 0.05) and cortical silent period durations (acquired neuromyotonia 212.8 +/- 6.9 ms; amyotrophic lateral sclerosis 181.1 +/- 4.3 ms, P < 0.0001) were significantly different between patients with acquired neuromyotonia and amyotrophic lateral sclerosis. Threshold tracking transcranial magnetic stimulation established corticomotoneuronal integrity

  2. Immunogenicity of bioactive magnetic nanoparticles: natural and acquired antibodies.

    PubMed

    Ziv, Ofra; Avtalion, Ramy R; Margel, Shlomo

    2008-06-15

    Uniform magnetic nanoparticles (MNP) were prepared by nucleation followed by controlled growth of maghemite thin films onto porcine gelatin nuclei. The formed gelatin containing MNP (Gel-MNP) were then coated with dextran (Gel-MNP-Dex) followed by human serum albumin (Gel-MNP-Dex-HSA). Since these MNP are designated for clinical applications, studies concerning the immunogenicity of their antigenic components (porcine gelatin, dextran, and HSA) have been performed in BALB-C mice. These studies demonstrated that plasma of nonimmunized mice already contains basal levels of natural antibodies against all of these antigenic components. This work also demonstrated that the conjugated gelatin is a weak immunogen: Intraperitoneal injection of the various MNP (Gel-MNP, Gel-MNP-Dex dispersed in PBS emulsified with Incomplete Freund's Adjuvant (IFA) mineral oil and Gel-MNP-Dex-HSA dispersed in PBS) did not increase significantly the acquired anti-gelatin antibody titers. Exceptional behavior was observed following immunization with Gel-MNP-Dex-HSA dispersed in PBS emulsified with IFA, which exhibited an adjuvant effect and turned gelatin into a stronger immunogen. In contrast to gelatin, the conjugated HSA and dextran were found to be strong immunogens. The possibility that the various MNP will not induce an autoimmune response as a result of their clinical use is discussed in the contest of the protective role of the natural antibodies.

  3. Functional Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Voos, Avery; Pelphrey, Kevin

    2013-01-01

    Functional magnetic resonance imaging (fMRI), with its excellent spatial resolution and ability to visualize networks of neuroanatomical structures involved in complex information processing, has become the dominant technique for the study of brain function and its development. The accessibility of in-vivo pediatric brain-imaging techniques…

  4. Superconducting combined function magnets

    SciTech Connect

    Hahn, H.; Fernow, R.C.

    1983-01-01

    Superconducting accelerators and storage rings, presently under construction or in the design phase, are based on separate dipole and quadrupole magnets. It is here suggested that a hybrid lattice configuration consisting of dipoles and combined function gradient magnets would: (1) reduce the number of magnet units and their total cost; and (2) increase the filling factor and thus the energy at a given field. Coil cross sections are presented for the example of the Brookhaven Colliding Beam Accelerator. An asymmetric two-layer cable gradient magnet would have transfer functions of 10.42 G/A and 0.628 G cm/sup -1//A versus 15.77 G/A and 2.03 G cm/sup -1//A of the present separate dipoles and quadrupoles.

  5. [Acquired platelet function disorders: pathogenesis, classification, frequency, diagnosis, clinical management].

    PubMed

    Scharf, R E

    2008-12-01

    Given the high consumption of pharmacological agents in western societies, it is not surprising at all that drugs represent the most common cause of acquired platelet dysfunction. While acetylsalicylic acid, clopigogrel and integrin alphaIIbbeta3 (GPIIb-IIIa) receptor antagonists are well-known as prototypes of antiplatelet drugs, other widely used agents including non-steroidal anti-inflammatory drugs, antibiotics, serotonin reuptake inhibitors, and volume expanders can also impair platelet function and cause or aggravate haemorrhages. Besides pharmacological agents, certain clinical conditions are often associated with qualitative platelet disorders and bleeding diathesis. Consequently, in contrast to inherited platelet disorders, acquired platelet function defects are much more frequent in clinical practice and deserve special attention. Their pathogenesis is widespread and heterogeneous with various, sometimes overlapping abnormalities. Moreover, acquired platelet dysfunctions can occur at any age and range in severity from mild to life-threatening haemorrhages. Due to their heterogeneity, acquired platelet function disorders will be classified and discussed according to the underlying clinical setting or disease.

  6. Functional magnetic microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Landel, Robert F. (Inventor)

    1981-01-01

    Functional magnetic particles are formed by dissolving a mucopolysaccharide such as chitosan in acidified aqueous solution containing a mixture of ferrous chloride and ferric chloride. As the pH of the solution is raised magnetite is formed in situ in the solution by raising the pH. The dissolved chitosan is a polyelectrolyte and forms micelles surrounding the granules at pH of 8-9. The chitosan precipitates on the granules to form microspheres containing the magnetic granules. On addition of the microspheres to waste aqueous streams containing dissolved ions, the hydroxyl and amine functionality of the chitosan forms chelates binding heavy metal cations such as lead, copper, and mercury and the chelates in turn bind anions such as nitrate, fluoride, phosphate and borate.

  7. Functional Magnetic Resonance Imaging Methods

    PubMed Central

    Chen, Jingyuan E.; Glover, Gary H.

    2015-01-01

    Since its inception in 1992, Functional Magnetic Resonance Imaging (fMRI) has become an indispensible tool for studying cognition in both the healthy and dysfunctional brain. FMRI monitors changes in the oxygenation of brain tissue resulting from altered metabolism consequent to a task-based evoked neural response or from spontaneous fluctuations in neural activity in the absence of conscious mentation (the “resting state”). Task-based studies have revealed neural correlates of a large number of important cognitive processes, while fMRI studies performed in the resting state have demonstrated brain-wide networks that result from brain regions with synchronized, apparently spontaneous activity. In this article, we review the methods used to acquire and analyze fMRI signals. PMID:26248581

  8. Functional magnetic resonance imaging.

    PubMed

    Buchbinder, Bradley R

    2016-01-01

    Functional magnetic resonance imaging (fMRI) maps the spatiotemporal distribution of neural activity in the brain under varying cognitive conditions. Since its inception in 1991, blood oxygen level-dependent (BOLD) fMRI has rapidly become a vital methodology in basic and applied neuroscience research. In the clinical realm, it has become an established tool for presurgical functional brain mapping. This chapter has three principal aims. First, we review key physiologic, biophysical, and methodologic principles that underlie BOLD fMRI, regardless of its particular area of application. These principles inform a nuanced interpretation of the BOLD fMRI signal, along with its neurophysiologic significance and pitfalls. Second, we illustrate the clinical application of task-based fMRI to presurgical motor, language, and memory mapping in patients with lesions near eloquent brain areas. Integration of BOLD fMRI and diffusion tensor white-matter tractography provides a road map for presurgical planning and intraoperative navigation that helps to maximize the extent of lesion resection while minimizing the risk of postoperative neurologic deficits. Finally, we highlight several basic principles of resting-state fMRI and its emerging translational clinical applications. Resting-state fMRI represents an important paradigm shift, focusing attention on functional connectivity within intrinsic cognitive networks.

  9. Monocyte function in the acquired immune deficiency syndrome. Defective chemotaxis.

    PubMed Central

    Smith, P D; Ohura, K; Masur, H; Lane, H C; Fauci, A S; Wahl, S M

    1984-01-01

    The ineffective immune response in patients with the acquired immune deficiency syndrome (AIDS) contributes to severe and widespread infections and unrestricted growth by certain tumors. To determine whether monocyte dysfunction contributes to this immunosuppressed condition, we investigated monocyte chemotaxis in patients with AIDS. Using three different chemotactic stimuli, N-formylmethionylleucylphenylalanine, lymphocyte-derived chemotactic factor, and C5a des Arg, we studied the chemotactic responses of monocytes from seven homosexual men with AIDS, three homosexuals with lymphadenopathy and an abnormal immunological profile, seven healthy homosexual men, and 23 heterosexual control individuals. Monocytes from each of the AIDS patients with Kaposi's sarcoma and/or opportunistic infection exhibited a marked reduction in chemotaxis to all stimuli compared with the healthy control subjects. The reduced chemotactic responses were observed over a wide range of concentrations for each stimulus. Monocytes from AIDS patients who had clinically apparent opportunistic infection(s) exhibited a greater reduction in monocyte migration to all three stimuli than monocytes from the AIDS patient with only Kaposi's sarcoma. Monocytes from each of three homosexuals with lymphadenopathy and an abnormal immunological profile exhibited decreased chemotactic responses that were intermediate between those of the AIDS patients and the healthy heterosexual control subjects. In contrast to these findings, monocytes from each of seven healthy homosexuals exhibited normal chemotactic responses to the same stimuli. In addition, monocytes from AIDS patients exhibited reduced chemotaxis to soluble products of Giardia lamblia, one of several protozoan parasites prevalent in AIDS patients. Thus the immune abnormality in AIDS, previously thought to involve only the T-, B-, and natural killer lymphocytes, extends to the monocyte-macrophage. Defective monocyte migratory function may contribute to

  10. A measurement setup for acquiring the local magnetic properties of plastically deformed soft magnetic materials

    SciTech Connect

    Bi Shasha; Sutor, Alexander; Lerch, Reinhard; Xiao Yunshi

    2011-04-01

    This paper introduces a new measurement setup for extraction of the local magnetic properties. With the help of finite element method simulations, modifications are made on the previous double-C-yoke method. Small dimension measuring coils are applied in the stray field produced by the magnetic circuit to evaluate the local magnetic properties of the specified part of the specimen. Through the measurements with the plastically deformed materials at different temperatures, it indicates that the magnetic properties of soft magnetic materials are quite sensitive to plastic straining. After high-temperature thermal treatment on the plastically deformed specimen, the local magnetic properties exhibit an obvious recovery.

  11. Familial Essential Tremor Studied With Functional Magnetic Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Hernandez, A.; Salgado, P.; Gil, A.; Barrios, F. A.

    2003-09-01

    Functional Magnetic Resonance Imaging has become an important analytical tool to study neurodegenerative diseases. We applied the EPI-BOLD functional Magnetic Resonance Imaging technique to acquire functional images of patients with familial essential tremor (FET) disorder and healthy control volunteers, during a motor task activity. Functional and anatomic images were used to produce the brain activation maps of the patients and volunteers. These functional maps of the primary somatosensorial and motor cortexes of patients and control subjects were compared for functional differences per subject. The averaged functional brain images of eight of each case were acquired were, it can be clearly observed the differences in active zones. The results presented in this work show that there are differences in the functional maps during motor task activation between control subjects and FET patients suggesting a cerebral functional reorganization that can be mapped with BOLD-fMRI.

  12. Functional magnetic resonance imaging studies of language.

    PubMed

    Small, Steven L; Burton, Martha W

    2002-11-01

    Functional neuroimaging of language builds on almost 150 years of study in neurology, psychology, linguistics, anatomy, and physiology. In recent years, there has been an explosion of research using functional imaging technology, especially positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), to understand the relationship between brain mechanisms and language processing. These methods combine high-resolution anatomic images with measures of language-specific brain activity to reveal neural correlates of language processing. This article reviews some of what has been learned about the neuroanatomy of language from these imaging techniques. We first discuss the normal case, organizing the presentation according to the levels of language, encompassing words (lexicon), sound structure (phonemes), and sentences (syntax and semantics). Next, we delve into some unusual language processing circumstances, including second languages and sign languages. Finally, we discuss abnormal language processing, including developmental and acquired dyslexia and aphasia.

  13. Memory functions of magnetic skyrmions

    NASA Astrophysics Data System (ADS)

    Koshibae, Wataru; Kaneko, Yoshio; Iwasaki, Junichi; Kawasaki, Masashi; Tokura, Yoshinori; Nagaosa, Naoto

    2015-05-01

    We study, by microsimulation on the chiral magnets, the elementary functions of magnetic skyrmions and the design principles of skyrmionic memory devices. The external stimuli, such as local heating, magnetic field, electric field and electric current, trigger the creation and annihilation of the skyrmion. These procedures, corresponding to the writing and erasing operations, are achieved typically within of the order of nano or pico seconds. We also examine the current driven motion of the skyrmions and find that the gyro-dynamics, which is induced by the topological nature of the skyrmion, leads to the variety of useful functions including the remarkable enhancement of the spin-transfer-torque effect. These features are shown to be advantageous for (a) high-density data-storage, (b) nonvolatile memory, and (c) ultra-low current and energy cost manipulation.

  14. Lift outs: how to acquire a high-functioning team.

    PubMed

    Groysberg, Boris; Abrahams, Robin

    2006-12-01

    More and more, expanding companies are hiring high-functioning groups of people who have been working together effectively within one company and can rapidly come up to speed in a new environment. These lifted-out teams don't need to get acquainted with one another or to establish shared values, mutual accountability, or group norms; their long-standing relationships and trust help them make an impact very quickly. Of course, the process is not without risks: A failed lift out can lead to loss of money, opportunity, credibility, and even native talent. Boris Groysberg and Robin Abrahams studied more than 40 high-profile moves and interviewed team leaders in multiple industries and countries to examine the risks and opportunities that lift outs present. They concluded that, regardless of industry, nationality, or size of the team, a successful lift out unfolds over four consecutive, interdependent stages that must be meticulously managed. In the courtship stage, the hiring company and the leader of the targeted team determine whether the proposed move is, in fact, a good idea, and then define their business goals and discuss strategies. At the same time, the team leader discusses the potential move with the other members of his or her group to assess their level of interest and prepare them for the change. The second stage involves the integration of the team leader with the new company's top leadership. This part of the process ensures the team's access to senior executives-the most important factor in a lift out's success. Operational integration is the focus of the third stage. Ideally, teams will start out working with the same or similar clients, vendors, and industry standards. The fourth stage entails full cultural integration. To succeed, the lifted-out team members must be willing to re-earn credibility by proving their value and winning their new colleagues' trust.

  15. Technical considerations for functional magnetic resonance imaging analysis.

    PubMed

    Conklin, Chris J; Faro, Scott H; Mohamed, Feroze B

    2014-11-01

    Clinical application of functional magnetic resonance imaging (fMRI) based on blood oxygenation level-dependent (BOLD) effect has increased over the past decade because of its ability to map regional blood flow in response to brain stimulation. This mapping is primarily achieved by exploiting the BOLD effect precipitated by changes in the magnetic properties of hemoglobin. BOLD fMRI has utility in neurosurgical planning and mapping neuronal functional connectivity. Conventional echo planar imaging techniques are used to acquire stimulus-driven fMR imaging BOLD data. This article highlights technical aspects of fMRI data analysis to make it more accessible in clinical settings.

  16. Magnetic dipole moment of a spherical shell with TRM acquired in a field of internal origin. [Thermoremanent Magnetization implications for lunar magnetic field

    NASA Technical Reports Server (NTRS)

    Srnka, L. J.

    1976-01-01

    The acquisition of thermoremanent magnetization (TRM) by a cooling spherical shell is studied for internal magnetizing dipole fields, using Runcorn's (1975) theorems on magnetostatics. If the shell cools progressively inward, inner regions acquire TRM in a net field composed of the dipole source term plus a uniform field due to the outer magnetized layers. In this case, the global dipole moment and external remanent field are nonzero when the whole shell has cooled below the Curie point and the source dipole has disappeared. The remanent field outside the shell is found to depend on the thickness, radii, and cooling rate of the shell, as well as the coefficient of TRM and the intensity of the magnetizing field. Some implications for the moon's remanent dipole moment are discussed.

  17. 3D linear inversion of magnetic susceptibility data acquired by frequency domain EMI

    NASA Astrophysics Data System (ADS)

    Thiesson, J.; Tabbagh, A.; Simon, F.-X.; Dabas, M.

    2017-01-01

    Low induction number EMI instruments are able to simultaneously measure a soil's apparent magnetic susceptibility and electrical conductivity. This family of dual measurement instruments is highly useful for the analysis of soils and archeological sites. However, the electromagnetic properties of soils are found to vary over considerably different ranges: whereas their electrical conductivity varies from ≤ 0.1 to ≥ 100 mS/m, their relative magnetic permeability remains within a very small range, between 1.0001 and 1.01 SI. Consequently, although apparent conductivity measurements need to be inverted using non-linear processes, the variations of the apparent magnetic susceptibility can be approximated through the use of linear processes, as in the case of the magnetic prospection technique. Our proposed 3D inversion algorithm starts from apparent susceptibility data sets, acquired using different instruments over a given area. A reference vertical profile is defined by considering the mode of the vertical distributions of both the electrical resistivity and of the magnetic susceptibility. At each point of the mapped area, the reference vertical profile response is subtracted to obtain the apparent susceptibility variation dataset. A 2D horizontal Fourier transform is applied to these variation datasets and to the dipole (impulse) response of each instrument, a (vertical) 1D inversion is performed at each point in the spectral domain, and finally the resulting dataset is inverse transformed to restore the apparent 3D susceptibility variations. It has been shown that when applied to synthetic results, this method is able to correct the apparent deformations of a buried object resulting from the geometry of the instrument, and to restore reliable quantitative susceptibility contrasts. It also allows the thin layer solution, similar to that used in magnetic prospection, to be implemented. When applied to field data it initially delivers a level of contrast

  18. [Presurgical functional magnetic resonance imaging].

    PubMed

    Stippich, C

    2010-02-01

    Functional magnetic resonance imaging (fMRI) is an important and novel neuroimaging modality for patients with brain tumors. By non-invasive measurement, localization and lateralization of brain activiation, most importantly of motor and speech function, fMRI facilitates the selection of the most appropriate and sparing treatment and function-preserving surgery. Prerequisites for the diagnostic use of fMRI are the application of dedicated clinical imaging protocols and standardization of the respective imaging procedures. The combination with diffusion tensor imaging (DTI) also enables tracking and visualization of important fiber bundles such as the pyramidal tract and the arcuate fascicle. These multimodal MR data can be implemented in computer systems for functional neuronavigation or radiation treatment. The practicability, accuracy and reliability of presurgical fMRI have been validated by large numbers of published data. However, fMRI cannot be considered as a fully established modality of diagnostic neuroimaging due to the lack of guidelines of the responsible medical associations as well as the lack of medical certification of important hardware and software components. This article reviews the current research in the field and provides practical information relevant for presurgical fMRI.

  19. Reorganization of Functional Connectivity as a Correlate of Cognitive Recovery in Acquired Brain Injury

    ERIC Educational Resources Information Center

    Castellanos, Nazareth P.; Paul, Nuria; Ordonez, Victoria E.; Demuynck, Olivier; Bajo, Ricardo; Campo, Pablo; Bilbao, Alvaro; Ortiz, Tomas; del-Pozo, Francisco; Maestu, Fernando

    2010-01-01

    Cognitive processes require a functional interaction between specialized multiple, local and remote brain regions. Although these interactions can be strongly altered by an acquired brain injury, brain plasticity allows network reorganization to be principally responsible for recovery. The present work evaluates the impact of brain injury on…

  20. Functional Magnetic Resonance Imaging and Pediatric Anxiety

    ERIC Educational Resources Information Center

    Pine, Daniel S.; Guyer, Amanda E.; Leibenluft, Ellen; Peterson, Bradley S.; Gerber, Andrew

    2008-01-01

    The use of functional magnetic resonance imaging in investigating pediatric anxiety disorders is studied. Functional magnetic resonance imaging can be utilized in demonstrating parallels between the neural architecture of difference in anxiety of humans and the neural architecture of attention-orienting behavior in nonhuman primates or rodents.…

  1. Capable of Suicide: A Functional Model of the Acquired Capability Component of the Interpersonal-Psychological Theory of Suicide

    ERIC Educational Resources Information Center

    Smith, Phillip N.; Cukrowicz, Kelly C.

    2010-01-01

    A functional model of the acquired capability for suicide, a component of Joiner's (2005) Interpersonal-Psychological Theory of Suicide, is presented. A component of Joiner's (2005) Interpersonal-Psychological Theory of Suicide a functional model of the acquired capability for suicide is presented. The model integrates the points discussed by…

  2. Magnetic fields and density functional theory

    SciTech Connect

    Salsbury Jr., Freddie

    1999-02-01

    A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.

  3. Functional Nanomaterials Useful for Magnetic Refrigeration Systems

    NASA Astrophysics Data System (ADS)

    Aslani, Amir

    Magnetic refrigeration is an emerging energy efficient and environmentally friendly refrigeration technology. The principle of magnetic refrigeration is based on the effect of varying a magnetic field on the temperature change of a magnetocaloric material (refrigerant). By applying a magnetic field, the magnetic moments of a magnetic material tend to align parallel to it, and the thermal energy released in this process heats the material. Reversibly, the magnetic moments become randomly oriented when the magnetic field is removed, and the material cools down. The heating and the cooling of a refrigerant in response to a changing magnetic field is similar to the heating and the cooling of a gaseous medium in response to an adiabatic compression and expansion in a conventional refrigeration system. One requirement to make a practical magnetic refrigerator is to have a large temperature change per unit of applied magnetic field, with sufficiently wide operating temperature. So far, no commercially viable magnetic refrigerator has been built primarily due to the low temperature change of bulk refrigerants, the added burden of hysteresis, and the system's low cooling capacity. The purpose of this dissertation is to explore magnetic refrigeration system. First, the Active Magnetic Regenerator (AMR) system built by Shir et al at the GWU's Institute for Magnetics Research (IMR) is optimized by tuning the heat transfer medium parameters and system's operating conditions. Next, by reviewing literature and works done so far on refrigerants, a number of materials that may be suitable to be used in magnetic refrigeration technology were identified. Theoretical work by Bennett et al showed an enhancement in magnetocaloric effect of magnetic nanoparticles. Research was performed on functional magnetic nanoparticles and their use in magnetic refrigeration technology. Different aspects such as the size, shape, chemical composition, structure and interaction of the nanoparticle with

  4. Tutte polynomial in functional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    García-Castillón, Marlly V.

    2015-09-01

    Methods of graph theory are applied to the processing of functional magnetic resonance images. Specifically the Tutte polynomial is used to analyze such kind of images. Functional Magnetic Resonance Imaging provide us connectivity networks in the brain which are represented by graphs and the Tutte polynomial will be applied. The problem of computing the Tutte polynomial for a given graph is #P-hard even for planar graphs. For a practical application the maple packages "GraphTheory" and "SpecialGraphs" will be used. We will consider certain diagram which is depicting functional connectivity, specifically between frontal and posterior areas, in autism during an inferential text comprehension task. The Tutte polynomial for the resulting neural networks will be computed and some numerical invariants for such network will be obtained. Our results show that the Tutte polynomial is a powerful tool to analyze and characterize the networks obtained from functional magnetic resonance imaging.

  5. Functionalized magnetic nanoparticle analyte sensor

    DOEpatents

    Yantasee, Wassana; Warner, Maryin G; Warner, Cynthia L; Addleman, Raymond S; Fryxell, Glen E; Timchalk, Charles; Toloczko, Mychailo B

    2014-03-25

    A method and system for simply and efficiently determining quantities of a preselected material in a particular solution by the placement of at least one superparamagnetic nanoparticle having a specified functionalized organic material connected thereto into a particular sample solution, wherein preselected analytes attach to the functionalized organic groups, these superparamagnetic nanoparticles are then collected at a collection site and analyzed for the presence of a particular analyte.

  6. Dissipation function in a magnetic field (Review)

    NASA Astrophysics Data System (ADS)

    Gurevich, V. L.

    2015-07-01

    The dissipation function is introduced to describe the behavior of the system of harmonic oscillations interacting with the environment (thermostat). This is a quadratic function of generalized velocities, which determines the rate of dissipation of the mechanical energy in the system. It was assumed earlier (Landau, Lifshitz) that the dissipation function can be introduced only in the absence of magnetic field. In the present review based on the author's studies, it has been shown how the dissipation function can be introduced in the presence of a magnetic field B. In a magnetic field, both dissipative and nondissipative responses arise as a response to perturbation and are expressed in terms of kinetic coefficients. The matrix of nondissipative coefficients can be obtained to determine an additional term formally including it into the equations of motion, which still satisfy the energy conservation law. Then, the dissipative part of the matrix can be considered in exactly the same way as without magnetic field, i.e., it defines the dissipation loss. As examples, the propagation and absorption of ultrasound in a metal or a semiconductor in a magnetic field have been considered using two methods: (i) the method based on the phenomenological theory using the equations of the theory of elasticity and (ii) the method based on the microscopic approach by analyzing and solving the kinetic equation. Both examples are used to illustrate the approach with the dissipation function.

  7. Functional characterization and phylogenetic analysis of acquired and intrinsic macrolide phosphotransferases in the Bacillus cereus group.

    PubMed

    Wang, Chao; Sui, Zhihai; Leclercq, Sébastien Olivier; Zhang, Gang; Zhao, Meilin; Chen, Weiqi; Feng, Jie

    2015-05-01

    The Bacillus cereus group is composed of Gram-positive spore-forming bacteria of clinical and ecological importance. More than 200 B. cereus group isolates have been sequenced. However, there are few reports of B. cereus group antibiotic resistance genes. This study identified two functional classes of macrolide phosphotransferases (Mphs) in the B. cereus group. Cluster A Mphs inactivate 14- and 15-membered macrolides while Cluster B Mphs inactivate 14-, 15- and 16-membered compounds. The genomic region surrounding the Cluster B Mph gene is related to various plasmid sequences, suggesting that this gene is an acquired resistance gene. In contrast, the Cluster A Mph gene is located in a chromosomal region conserved among all B. cereus group isolates, and data indicated that it was acquired early in the evolution of the group. Therefore, the Cluster A gene can be considered an intrinsic resistance gene. However, the gene itself is not present in all strains and our comparative genomics analyses showed that it is exchanged among strains of the B. cereus group by the mean of homologous recombination. These results provide an alternative mechanism to intrinsic resistance.

  8. A functional difference between native and horizontally acquired genes in bdelloid rotifers.

    PubMed

    Barbosa, Elton G G; Crisp, Alastair; Broadbent, Sarah E; Carrillo, Martina; Boschetti, Chiara; Tunnacliffe, Alan

    2016-09-15

    The form of RNA processing known as SL trans-splicing involves the transfer of a short conserved sequence, the spliced leader (SL), from a noncoding SL RNA to the 5' ends of mRNA molecules. SL trans-splicing occurs in several animal taxa, including bdelloid rotifers (Rotifera, Bdelloidea). One striking feature of these aquatic microinvertebrates is the large proportion of foreign genes, i.e. those acquired by horizontal gene transfer from other organisms, in their genomes. However, whether such foreign genes behave similarly to native genes has not been tested in bdelloids or any other animal. We therefore used a combination of experimental and computational methods to examine whether transcripts of foreign genes in bdelloids were SL trans-spliced, like their native counterparts. We found that many foreign transcripts contain SLs, use similar splice acceptor sequences to native genes, and are able to undergo alternative trans-splicing. However, a significantly lower proportion of foreign mRNAs contains SL sequences than native transcripts. This demonstrates a novel functional difference between foreign and native genes in bdelloids and suggests that SL trans-splicing is not essential for the expression of foreign genes, but is acquired during their domestication.

  9. Acquiring background knowledge for machine learning using function decomposition: a case study in rheumatology.

    PubMed

    Zupan, B; Dzeroski, S

    1998-01-01

    Domain or background knowledge is often needed in order to solve difficult problems of learning medical diagnostic rules. Earlier experiments have demonstrated the utility of background knowledge when learning rules for early diagnosis of rheumatic diseases. A particular form of background knowledge comprising typical co-occurrences of several groups of attributes was provided by a medical expert. This paper explores the possibility of automating the process of acquiring background knowledge of this kind and studies the utility of such methods in the problem domain of rheumatic diseases. A method based on function decomposition is proposed that identifies typical co-occurrences for a given set of attributes. The method is evaluated by comparing the typical co-occurrences it identifies as well as their contribution to the performance of machine learning algorithms, to the ones provided by a medical expert.

  10. [The functional properties and oxidative modification of plasma and neutrophil proteins in community-acquired pneumonia].

    PubMed

    Stepovaia, E A; Petina, G V; Zhavoronok, T V; Riazantseva, N V; Ivanov, V V; Ageeva, T S; Tetenev, F F; Bezmenova, M A

    2010-03-01

    The functional properties of neutrophils (the activity of myeloperoxidase and the production of hydroxyl radical) were studied in community-acquired pneumonia (CAP) predominantly with the alveolar and interstitial types of lung parenchymal infiltration. Protein oxidative modification was estimated from the content of protein carbonyl derivatives in neutrophilic leukocytes and plasma and from the plasma concentration of bityrosine and oxidized tryptophan in patients with CAP. The production of hydroxyl radical and the activity of myeloperoxidase in the neutrophils of patients with CAP were increased and did not depend on the type of lung tissue infiltration. The development of oxidative stress in CAP was accompanied by the substantiation activation of protein oxidative modification processes in the neutrophilic leukocytes and plasma.

  11. Constrained density functional for noncollinear magnetism

    NASA Astrophysics Data System (ADS)

    Ma, Pui-Wai; Dudarev, S. L.

    2015-02-01

    Energies of arbitrary small- and large-angle noncollinear excited magnetic configurations are computed using a highly accurate constrained density functional theory approach. Numerical convergence and accuracy are controlled by the choice of Lagrange multipliers λI entering the constraining conditions. The penalty part Ep of the constrained energy functional at its minimum is shown to be inversely proportional to λI, enabling a simple, robust, and accurate iterative procedure to be followed to find a convergent solution. The method is implemented as a part of ab initio vasp package, and applied to the investigation of noncollinear B2-like and <001 > double-layer antiferromagnetic configurations of bcc iron, Fe2 dimer, and amorphous iron. Forces acting on atoms depend on the orientations of magnetic moments, and the proposed approach enables constrained self-consistent noncollinear magnetic and structural relaxation of large atomic systems to be carried out.

  12. Coil Design for Functional Magnetic Stimulation of the Inspiratory Muscles

    DTIC Science & Technology

    2007-11-02

    Coil design for functional magnetic stimulation of the inspiratory muscles Ian N. Hsiao, Ph.D., member IEEE, Ercheng Zhu, MD, PhD, Vernon Lin...new magnetic coil (MC) for effective functional magnetic stimulation (FMS) of inspiratory muscles in human subjects. Part 1 of the study emphasized...2 is reported in another paper titled “Racetrack magnetic coil for functional magnetic stimulation of the inspiratory muscles – toward magnetic

  13. Optimization of multiply acquired magnetic flux density B(z) using ICNE-Multiecho train in MREIT.

    PubMed

    Nam, Hyun Soo; Kwon, Oh In

    2010-05-07

    The aim of magnetic resonance electrical impedance tomography (MREIT) is to visualize the electrical properties, conductivity or current density of an object by injection of current. Recently, the prolonged data acquisition time when using the injected current nonlinear encoding (ICNE) method has been advantageous for measurement of magnetic flux density data, Bz, for MREIT in the signal-to-noise ratio (SNR). However, the ICNE method results in undesirable side artifacts, such as blurring, chemical shift and phase artifacts, due to the long data acquisition under an inhomogeneous static field. In this paper, we apply the ICNE method to a gradient and spin echo (GRASE) multi-echo train pulse sequence in order to provide the multiple k-space lines during a single RF pulse period. We analyze the SNR of the measured multiple B(z) data using the proposed ICNE-Multiecho MR pulse sequence. By determining a weighting factor for B(z) data in each of the echoes, an optimized inversion formula for the magnetic flux density data is proposed for the ICNE-Multiecho MR sequence. Using the ICNE-Multiecho method, the quality of the measured magnetic flux density is considerably increased by the injection of a long current through the echo train length and by optimization of the voxel-by-voxel noise level of the B(z) value. Agarose-gel phantom experiments have demonstrated fewer artifacts and a better SNR using the ICNE-Multiecho method. Experimenting with the brain of an anesthetized dog, we collected valuable echoes by taking into account the noise level of each of the echoes and determined B(z) data by determining optimized weighting factors for the multiply acquired magnetic flux density data.

  14. Acquired midfoot deformity and function in individuals with diabetes and peripheral neuropathy

    PubMed Central

    Hastings, Mary K.; Mueller, Michael J.; Woodburn, James; Strube, Michael J; Commean, Paul; Johnson, Jeffrey E.; Cheuy, Victor; Sinacore, David R.

    2015-01-01

    Background Diabetes mellitus related medial column foot deformity is a major contributor to ulceration and amputation. However, little is known about the relationship between medial column alignment and function and the integrity of the soft tissues that support and move the medial column. The purposes of this study were to determine the predictors of medial column alignment and function in people with diabetes and peripheral neuropathy. Methods 23 participants with diabetes and neuropathy had radiographs, heel rise kinematics, magnetic resonance imaging and isokinetic muscle testing to measure: 1) medial column alignment (Meary’s angle- the angle between the 1st metatarsal longitudinal axis and the talar head and neck), 2) medial column function (forefoot relative to hindfoot plantarflexion during heel rise), 3) intrinsic foot muscle and fat volume, ratio of posterior tibialis to flexor digitorum tendon volume, 4) plantar fascia function (Meary’s angle change from toes flat to extended) and 5) plantarflexor peak torque. Predictors of medial column alignment and function were determined using simultaneous entry multiple regression. Findings Posterior tibialis to flexor digitorum tendon volume ratio and intrinsic foot muscle volume were significant predictors of medial column alignment (p<.05), accounting for 44% of the variance. Intrinsic foot fat volume and plantarflexor peak torque were significant predictors of medial column function (p<.05), accounting for 37% of the variance. Interpretation Deterioration of medial column supporting structures predicted alignment and function. Prospective research is required to monitor alignment, structure, and function over time to inform early intervention strategies to prevent deformity, ulceration, and amputation. PMID:26588885

  15. Two brief measures of executive function in the prediction of driving ability after acquired brain injury.

    PubMed

    Hargrave, David D; Nupp, Jason M; Erickson, Rey J

    2012-01-01

    The question of fitness to drive following acquired brain injury is commonly encountered in rehabilitation settings. Pre-driving assessments are usually performed prior to on-road assessments, but there is no uniformity as to the instruments employed. Neuropsychological tests are often employed to assess different functional domains. One domain that has been suggested to be critical to driving is executive functioning. The present study examined the utility of the Frontal Assessment Battery (FAB) and the Trail Making Test Part B (TMTB) in predicting on-road driving performance after stroke or traumatic brain injury. While the TMTB has previously been demonstrated to be useful in this regard, the FAB has never been examined for this purpose. Participants were 76 patients referred for driving assessment after diagnosis of stroke or traumatic brain injury. Results indicated that scores on the TMTB, but not the FAB, were significantly predictive of on-road driving performance (p < .05). A cutoff score of 90 seconds or greater on the TMTB correctly identified 77% of those failing on-road evaluation. Implications and limitations are discussed.

  16. Regulatory and Functional Aspects of Indolic Metabolism in Plant Systemic Acquired Resistance.

    PubMed

    Stahl, Elia; Bellwon, Patricia; Huber, Stefan; Schlaeppi, Klaus; Bernsdorff, Friederike; Vallat-Michel, Armelle; Mauch, Felix; Zeier, Jürgen

    2016-05-02

    Tryptophan-derived, indolic metabolites possess diverse functions in Arabidopsis innate immunity to microbial pathogen infection. Here, we investigate the functional role and regulatory characteristics of indolic metabolism in Arabidopsis systemic acquired resistance (SAR) triggered by the bacterial pathogen Pseudomonas syringae. Indolic metabolism is broadly activated in both P. syringae-inoculated and distant, non-inoculated leaves. At inoculation sites, camalexin, indol-3-ylmethylamine (I3A), and indole-3-carboxylic acid (ICA) are the major accumulating compounds. Camalexin accumulation is positively affected by MYB122, and the cytochrome P450 genes CYP81F1 and CYP81F2. Local I3A production, by contrast, occurs via indole glucosinolate breakdown by PEN2- dependent and independent pathways. Moreover, exogenous application of the defense hormone salicylic acid stimulates I3A generation at the expense of its precursor indol-3-ylmethylglucosinolate (I3M), and the SAR regulator pipecolic acid primes plants for enhanced P. syringae-induced activation of distinct branches of indolic metabolism. In uninfected systemic tissue, the metabolic response is more specific and associated with enhanced levels of the indolics I3A, ICA, and indole-3-carbaldehyde (ICC). Systemic indole accumulation fully depends on functional CYP79B2/3, PEN2, and MYB34/51/122, and requires functional SAR signaling. Genetic analyses suggest that systemically elevated indoles are dispensable for SAR and associated systemic increases of salicylic acid. However, soil-grown but not hydroponically -cultivated cyp79b2/3 and pen2 plants, both defective in indolic secondary metabolism, exhibit pre-induced immunity, which abrogates their intrinsic ability to induce SAR.

  17. Magnetic spectroscopy and microscopy of functional materials

    SciTech Connect

    Jenkins, Catherine Ann

    2011-05-01

    Heusler intermetallics Mn2Y Ga and X2MnGa (X; Y =Fe, Co, Ni) undergo tetragonal magnetostructural transitions that can result in half metallicity, magnetic shape memory, or the magnetocaloric effect. Understanding the magnetism and magnetic behavior in functional materials is often the most direct route to being able to optimize current materials for todays applications and to design novel ones for tomorrow. Synchrotron soft x-ray magnetic spectromicroscopy techniques are well suited to explore the the competing effects from the magnetization and the lattice parameters in these materials as they provide detailed element-, valence-, and site-specifc information on the coupling of crystallographic ordering and electronic structure as well as external parameters like temperature and pressure on the bonding and exchange. Fundamental work preparing the model systems of spintronic, multiferroic, and energy-related compositions is presented for context. The methodology of synchrotron spectroscopy is presented and applied to not only magnetic characterization but also of developing a systematic screening method for future examples of materials exhibiting any of the above effects. The chapter progression is as follows: an introduction to the concepts and materials under consideration (Chapter 1); an overview of sample preparation techniques and results, and the kinds of characterization methods employed (Chapter 2); spectro- and microscopic explorations of X2MnGa/Ge (Chapter 3); spectroscopic investigations of the composition series Mn2Y Ga to the logical Mn3Ga endpoint (Chapter 4); and a summary and overview of upcoming work (Chapter 5). Appendices include the results of a Think Tank for the Graduate School of Excellence MAINZ (Appendix A) and details of an imaging project now in progress on magnetic reversal and domain wall observation in the classical Heusler material Co2FeSi (Appendix B).

  18. Brightness of Solar Magnetic Elements As a Function of Magnetic Flux at High Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Kahil, F.; Riethmüller, T. L.; Solanki, S. K.

    2017-03-01

    We investigate the relationship between the photospheric magnetic field of small-scale magnetic elements in the quiet-Sun (QS) at disk center and the brightness at 214, 300, 313, 388, 397, and 525.02 nm. To this end, we analyzed spectropolarimetric and imaging time series acquired simultaneously by the Imaging Magnetograph eXperiment magnetograph and the SuFI filter imager on board the balloon-borne observatory {{S}}{{UNRISE}} during its first science flight in 2009, with high spatial and temporal resolution. We find a clear dependence of the contrast in the near ultraviolet and the visible on the line-of-sight component of the magnetic field, B LOS, which is best described by a logarithmic model. This function effectively represents the relationship between the Ca ii H-line emission and B LOS and works better than the power-law fit adopted by previous studies. This, along with the high contrast reached at these wavelengths, will help with determining the contribution of small-scale elements in the QS to the irradiance changes for wavelengths below 388 nm. At all wavelengths, including the continuum at 525.40 nm, the intensity contrast does not decrease with increasing B LOS. This result also strongly supports the fact that {{S}}{{UNRISE}} has resolved small strong magnetic field elements in the internetwork, resulting in constant contrasts for large magnetic fields in our continuum contrast at 525.40 nm versus the B LOS scatterplot, unlike the turnover obtained in previous observational studies. This turnover is due to the intermixing of the bright magnetic features with the dark intergranular lanes surrounding them.

  19. Linear constraint minimum variance beamformer functional magnetic resonance inverse imaging.

    PubMed

    Lin, Fa-Hsuan; Witzel, Thomas; Zeffiro, Thomas A; Belliveau, John W

    2008-11-01

    Accurate estimation of the timing of neural activity is required to fully model the information flow among functionally specialized regions whose joint activity underlies perception, cognition and action. Attempts to detect the fine temporal structure of task-related activity would benefit from functional imaging methods allowing higher sampling rates. Spatial filtering techniques have been used in magnetoencephalography source imaging applications. In this work, we use the linear constraint minimal variance (LCMV) beamformer localization method to reconstruct single-shot volumetric functional magnetic resonance imaging (fMRI) data using signals acquired simultaneously from all channels of a high density radio-frequency (RF) coil array. The LCMV beamformer method generalizes the existing volumetric magnetic resonance inverse imaging (InI) technique, achieving higher detection sensitivity while maintaining whole-brain spatial coverage and 100 ms temporal resolution. In this paper, we begin by introducing the LCMV reconstruction formulation and then quantitatively assess its performance using both simulated and empirical data. To demonstrate the sensitivity and inter-subject reliability of volumetric LCMV InI, we employ an event-related design to probe the spatial and temporal properties of task-related hemodynamic signal modulations in primary visual cortex. Compared to minimum-norm estimate (MNE) reconstructions, LCMV offers better localization accuracy and superior detection sensitivity. Robust results from both single subject and group analyses demonstrate the excellent sensitivity and specificity of volumetric InI in detecting the spatial and temporal structure of task-related brain activity.

  20. 'Fetal programming' and 'functional teratogenesis': on epigenetic mechanisms and prevention of perinatally acquired lasting health risks.

    PubMed

    Plagemann, Andreas

    2004-01-01

    Alterations of the intrauterine and early postnatal nutritional, metabolic, and hormonal environment may cause predispositions to the development of disorders and diseases in later life. Mechanisms responsible for this perinatally acquired 'malprogramming' still remain unclear. It has long been known, however, that hormones are environment-dependent organizers of the developing 'neuroendocrine-immune network', which regulates all fundamental processes of life. When present in nonphysiological concentrations during critical ontogenetic periods, hormones can therefore also act as 'endogenous functional teratogens'. Fetal and neonatal hyperinsulinism is a pathognomic feature in the offspring of diabetic mothers. Perinatal hyperinsulinism also occurs due to early postnatal overfeeding. Data obtained by our group indicate that elevated insulin concentrations during critical periods of perinatal life may induce a lasting 'malprogramming' of neuroendocrine systems regulating body weight, food intake, and metabolism. Similar characteristics may occur due to perinatal hyperleptinism, hypercortisolism etc. Since mechanisms of early 'programming' of obesity, diabetes, and the metabolic syndrome X are unclear, a complex 'neuroendocrine malprogramming' of the regulation of body weight and metabolism may provide a general etiopathogenetic concept in this context, exemplarily revealing critical new implications for chances and challenges of perinatal preventive medicine in the future.

  1. Functionalized magnetic nanoparticles for biomedical applications.

    PubMed

    Gudovan, Dragoș; Balaure, Paul Cătălin; Mihăiescu, Dan Eduard; Fudulu, Adrian; Purcăreanu, Bogdan; Radu, Mihai

    2015-01-01

    Functionalized magnetic nanoparticles followed two main directions in the field of biomedical applications: one direction is as image enhancing agents for magnetic resonance imaging (MRI) and the other is as drugdelivery devices for various biologically-active substances. A third field which just emerges in nanomedicine is the field of the so-called theranostic devices which combines in the same delivery vehicle both the therapeutic agent and the contrast substance. The advantages of using nanoparticles instead of larger carriers for delivery of both drug and image contrast enhancing agents will be highlighted throughout this review article. Despite the ever increasing number of articles reporting both in vitro and in vivo studies carried out on functionalized magnetic nanoparticles and envisaging their potential biomedical applications, only few formulations reached the phase of clinical trials and even fewer became marketed products. The perspectives in the field are open, since new drugs require new delivery devices and possibly new means of functionalization. At the same time, the field of nanomedicine also provides the opportunity to better exploit drugs that are already in clinical use by improving their bioavailability through appropriate nanoformulations.

  2. Magnetic resonance imaging depiction of acquired Dyke-Davidoff-Masson syndrome with crossed cerebro-cerebellar diaschisis: Report of two cases.

    PubMed

    Gupta, Ranjana; Joshi, Sandeep; Mittal, Amit; Luthra, Ishita; Mittal, Puneet; Verma, Vibha

    2015-01-01

    Acquired Dyke-Davidoff-Masson syndrome, also known as hemispheric atrophy, is characterized by loss of volume of one cerebral hemisphere from an insult in early life. Crossed cerebellar diaschisis refers to dysfunction/atrophy of cerebellar hemisphere which is secondary to contralateral supratentorial insult. We describe magnetic resonance imaging findings in two cases of acquired Dyke-Davidoff-Masson syndrome with crossed cerebro-cerebellar diaschisis.

  3. Initial Sensorimotor and Cardiovascular Data Acquired from Soyuz Landings: Establishing a Functional Performance Recovery Time Constant

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.; Kozlovskaya, I. B.; Kofman, I. S.; Tomilovskaya, E. S.; Cerisano, J. M.; Bloomberg, J. J.; Stenger, M. B.; Platts, S. H.; Rukavishnikov, I. V.; Fomina, E. V.; Lee, S. M. C.; Wood, S. J.; Mulavara, A. P.; Feiveson, A. H.; Fisher, E. A.

    2015-01-01

    testing (quiet stance sway) as well as cardiovascular responses during sensorimotor testing on all of the above measures. We have also collected motion sickness data associated with each of the postflight tests. When possible rudimentary cerebellar assessment was undertaken. In addition to the immediate post-landing collection of data, postflight data has been acquired twice more within 24 hours after landing and measurements continue until sensorimotor and cardiovascular responses have returned to preflight normative values (approximately 60 days postflight). SUMMARY The level of functional deficit observed in the crew tested to date is more severe than expected, clearly triggered by the acquisition of gravity loads immediately after landing when the demands for crew intervention in response to emergency operations will be greatest. Measureable performance parameters such as ability to perform a seat egress, recover from a fall or the ability to see clearly when walking, and related physiologic data (orthostatic responses) are required to provide an evidence base for characterizing programmatic risks and the degree of variability among crewmembers for exploration missions where the crew will be unassisted after landing. Overall, these early functional and related physiologic measurements will allow the estimation of nonlinear sensorimotor and cardiovascular recovery trends that have not been previously captured.

  4. Dynamic magnetic resonance imaging of endoscopic third ventriculostomy patency with differently acquired fast imaging with steady-state precession sequences.

    PubMed

    Lucic, Milos A; Koprivsek, Katarina; Kozic, Dusko; Spero, Martina; Spirovski, Milena; Lucic, Silvija

    2014-08-16

    The aim of the study was to determine the possibilities of two differently acquired two-dimensional fast imaging with steady-state precession (FISP 2D) magnetic resonance sequences in estimation of the third ventricle floor fenestration patency after endoscopic third ventriculostomy (ETV) in the subjects with aqueductal stenosis/obstruction.Fifty eight subjects (37 males, 21 females, mean age 27 years) with previously successfully performed ETV underwent brain MRI on 1.5T MR imager 3-6 months after the procedure. Two different FISP 2D sequences (one included in the standard vendor provided software package, and the other, experimentally developed by our team) were performed respectively at two fixed slice positions: midsagittal and perpendicular to the ETV fenestration, and displayed in a closed-loop cinematographic format in order to estimate the patency. The ventricular volume reduction has been observed as well.Cerebrospinal fluid (CSF) flow through the ETV fenestration was observed in midsagittal plane with both FISP 2D sequences in 93.11% subjects, while in 6.89% subjects the dynamic CSF flow MRI was inconclusive. In the perpendicular plane CSF flow through the ETV fenestration was visible only by use of experimentally developed FISP 2D (TR30/FA70) sequence. Postoperative volume reduction of lateral and third ventricle was detected in 67.24% subjects.Though both FISP 2D sequences acquired in midsagittal plane may be used to estimate the effects of performed ETV, due to achieved higher CSF pulsatile flow sensitivity, only the use of FISP 2D (TR30/FA70) sequence enables the estimation of the treatment effect in perpendicular plane in the absence of phase-contrast sequences. 

  5. Sensitive Flexible Magnetic Sensors using Organic Transistors with Magnetic-Functionalized Suspended Gate Electrodes.

    PubMed

    Zang, Yaping; Zhang, Fengjiao; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

    2015-12-22

    Utilizing a magnetic-functionalized suspended gate with combined features of outstanding conductivity, flexibility, and magnetic properties, flexible magnetic sensor based on an organic field-effect transistor (OFET), with a high sensitivity of 115.2% mT(-1) is demonstrated. Gate engineering enables the sensing devices to possess promising applications for flexible touchless switches and spatiallyresolved magnetic-imaging elements.

  6. Functionalized magnetic nanoparticles: A novel heterogeneous catalyst support

    EPA Science Inventory

    Functionalized magnetic nanoparticles have emerged as viable alternatives to conventional materials, as robust, high-surface-area heterogeneous catalyst supports. Post-synthetic surface modification protocol for magnetic nanoparticles has been developed that imparts desirable che...

  7. Acoustic noise during functional magnetic resonance imaging.

    PubMed

    Ravicz, M E; Melcher, J R; Kiang, N Y

    2000-10-01

    Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For studies of the auditory system, acoustic noise generated during fMRI can interfere with assessments of this activation by introducing uncontrolled extraneous sounds. As a first step toward reducing the noise during fMRI, this paper describes the temporal and spectral characteristics of the noise present under typical fMRI study conditions for two imagers with different static magnetic field strengths. Peak noise levels were 123 and 138 dB re 20 microPa in a 1.5-tesla (T) and a 3-T imager, respectively. The noise spectrum (calculated over a 10-ms window coinciding with the highest-amplitude noise) showed a prominent maximum at 1 kHz for the 1.5-T imager (115 dB SPL) and at 1.4 kHz for the 3-T imager (131 dB SPL). The frequency content and timing of the most intense noise components indicated that the noise was primarily attributable to the readout gradients in the imaging pulse sequence. The noise persisted above background levels for 300-500 ms after gradient activity ceased, indicating that resonating structures in the imager or noise reverberating in the imager room were also factors. The gradient noise waveform was highly repeatable. In addition, the coolant pump for the imager's permanent magnet and the room air-handling system were sources of ongoing noise lower in both level and frequency than gradient coil noise. Knowledge of the sources and characteristics of the noise enabled the examination of general approaches to noise control that could be applied to reduce the unwanted noise during fMRI sessions.

  8. Seeing the sound after visual loss: functional MRI in acquired auditory-visual synesthesia.

    PubMed

    Yong, Zixin; Hsieh, Po-Jang; Milea, Dan

    2017-02-01

    Acquired auditory-visual synesthesia (AVS) is a rare neurological sign, in which specific auditory stimulation triggers visual experience. In this study, we used event-related fMRI to explore the brain regions correlated with acquired monocular sound-induced phosphenes, which occurred 2 months after unilateral visual loss due to an ischemic optic neuropathy. During the fMRI session, 1-s pure tones at various pitches were presented to the patient, who was asked to report occurrence of sound-induced phosphenes by pressing one of the two buttons (yes/no). The brain activation during phosphene-experienced trials was contrasted with non-phosphene trials and compared to results obtained in one healthy control subject who underwent the same fMRI protocol. Our results suggest, for the first time, that acquired AVS occurring after visual impairment is associated with bilateral activation of primary and secondary visual cortex, possibly due to cross-wiring between auditory and visual sensory modalities.

  9. LA-MRSA CC398 differ from classical community acquired-MRSA and hospital acquired-MRSA lineages: functional analysis of infection and colonization processes.

    PubMed

    Ballhausen, Britta; Jung, Philipp; Kriegeskorte, André; Makgotlho, Phuti Edward; Ruffing, Ulla; von Müller, Lutz; Köck, Robin; Peters, Georg; Herrmann, Mathias; Ziebuhr, Wilma; Becker, Karsten; Bischoff, Markus

    2014-10-01

    Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of the clonal complex (CC) 398 became primarily known as colonizers of livestock animals. In the past few years, they have been increasingly introduced into hospitals with subsequent emergence of human infections. However, the (re-)adaptation to the human host is only incompletely understood. This study aimed to assess virulence properties of LA-MRSA CC398 by functional modeling of infection and colonization processes. A selection of 15 human LA-MRSA CC398 isolates and 11 pig-colonizing isolates were characterized regarding their virulence capacities and compared with human isolates of hospital-acquired (HA)-MRSA (CC5, CC22 and CC45) and community-associated (CA)-MRSA (CC8, CC30 and CC80) clonal lineages. Our investigations demonstrated that LA-MRSA CC398 adhered less efficient to human cells and human/bovine plasma fibronectin than CA-MRSA and HA-MRSA isolates. In contrast, the LA-MRSA CC398 isolates revealed a high cytotoxic potential comparable to certain CA-MRSA. Comparing the most prevalent LA-MRSA CC398 spa types (t011, t034, t108), isolates associated with spa t108 showed an increased adhesive and invasive potential paired with an increased ability to evade phagocytosis. The results underline both the pathogenic potential of LA-MRSA in general and the heterogeneity within the CC398 clade regarding the virulence characteristics of CC398 subpopulations. Assuming an ongoing (re-)adaptation to the human host combined with a huge reservoir of LA-MRSA CC398 in livestock and constant zoonotic transmission, the LA-MRSA CC398 lineage has the potential to pose a serious threat to human health.

  10. Evaluation of a Functional Model of Acquired Capability for Suicide in a Nationwide Sample of Korean Adults

    PubMed Central

    Lee, Joon Deuk; Cho, Maeng Je; Sohn, Jee Hoon; Park, Subin; Seong, Sujeong; Ahn, Joon Ho; Hahm, Bong-Jin

    2016-01-01

    Objective We examined a functional model of acquired capability for suicide, which was elaborated from the “Interpersonal-Psychological Theory of Suicide”. Methods A total of 6,027 Korean community subjects were recruited from The Korean Epidemiologic Catchment Area study conducted in 2011. The subjects were assessed systematically using the Korean version of the Composite International Diagnostic Interview version 2.1, the Korean version of the Barratt Impulsiveness Scale, and the Korean version of the Mood Disorder Questionnaire. We used structural equation modeling to identify potential factors contributing to a suicide attempt. Results Most aspects of the model were supported by the data and “the short-term enhancer for the acquired capability for suicide” had direct effects on suicide attempts. However, the suicidal planning effects of “the short-term enhancer for the acquired capability for suicide” were eliminated by the rule of parsimony. Conclusion The main finding was that “the short-term enhancer for the acquired capability for suicide” is relevant to suicide attempts when it's direct, indirect, and reciprocal effects are tested within a more complete system of relationships than found in existing studies. The implications of these findings are discussed with regard to future conceptual work and empirical research. PMID:27909450

  11. Functions of innate and acquired immune system are reduced in domestic pigeons (Columba livia domestica) given a low protein diet

    PubMed Central

    Mabuchi, Yuko; Frankel, Theresa L.

    2016-01-01

    Racing pigeons are exposed to and act as carriers of diseases. Dietary protein requirement for their maintenance has not been determined experimentally despite their being domesticated for over 7000 years. A maintenance nitrogen (protein) requirement (MNR) for pigeons was determined in a balance study using diets containing 6, 10 and 14% crude protein (CP). Then, the effects of feeding the diets were investigated to determine whether they were adequate to sustain innate and acquired immune functions. Nitrogen intake from the 6% CP diet was sufficient to maintain nitrogen balance and body weight in pigeons. However, the immune functions of phagocytosis, oxidative burst and lymphocyte proliferation in pigeons fed this diet were reduced compared with those fed 10 and 14% CP diets. Pigeons given the 6 and 10% CP diets had lower antibody titres following inoculation against Newcastle disease (ND) than those on the 14% CP diet. A confounding factor found on autopsy was the presence of intestinal parasites in some of the pigeons given the 6 and 10% CP diets; however, none of the pigeons used to measure MNR or acquired immunity to ND were infested with parasites. In conclusion, neither the 6 nor 10% CP diets adequately sustained acquired immune function of pigeons. PMID:27069640

  12. Functional Nanostructures for Magnetic and Energy Application

    NASA Astrophysics Data System (ADS)

    Zhou, Minjie

    Functional nanostructures serve as the basic building blocks for nanodevices and significant efforts have been devoted to their morphology control and properties optimization. In present study, four functional nanostructures, i.e., FePt/B4C multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite film, Ga-doped ZnO nanowire arrays, and CdSe nanotube arrays are designed, synthesized and characterized in detail, in which the first two are expected to be prominent candidates for ultrahigh-density magnetic storage media while the later two have potential applications in solar energy conversion. FePt/B4C multilayer thin films are deposited on silicon substrates using magnetron sputtering with different B4C layer thickness. Experimental results suggest that the B4C layers effectively serve as spacers to separate the FePt layers, making the multilayer configuration stable even after film annealing at elevated temperatures. On the other hand, B and C are found to be incorporated into the FePt layer, which is responsible for the FePt grain growth confinement and grain separation, and eventually affects the properties of the composite film. Based on the experimental results of multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite thin films on Si substrate are synthesized, in which a record coercivity of 2200 Oe is achieved compared to similar system. The size uniformity of the FePt nanoparticles, the well-defined particle-particle separation, together with the good magnetic property and high temperature thermal stability of the overall composite film, make it a very promising candidate for the ultrahigh density magnetic storage media. Semiconductor based one-dimensional nanostructures are investigated as promising building blocks for solar energy conversion devices. Two aspects are explored, aiming at increasing the energy conversion efficiency, i.e., facilitating electron transport and enhancing photon absorbing. In the first case

  13. Delineating potential epileptogenic areas utilizing resting functional magnetic resonance imaging (fMRI) in epilepsy patients.

    PubMed

    Pizarro, Ricardo; Nair, Veena; Meier, Timothy; Holdsworth, Ryan; Tunnell, Evelyn; Rutecki, Paul; Sillay, Karl; Meyerand, Mary E; Prabhakaran, Vivek

    2016-08-01

    Seizure localization includes neuroimaging like electroencephalogram, and magnetic resonance imaging (MRI) with limited ability to characterize the epileptogenic network. Temporal clustering analysis (TCA) characterizes epileptogenic network congruent with interictal epileptiform discharges by clustering together voxels with transient signals. We generated epileptogenic areas for 12 of 13 epilepsy patients with TCA, congruent with different areas of seizure onset. Resting functional MRI (fMRI) scans are noninvasive, and can be acquired quickly, in patients with different levels of severity and function. Analyzing resting fMRI data using TCA is quick and can complement clinical methods to characterize the epileptogenic network.

  14. Properties of Magnetic Reconnection as a function of magnetic shear

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Daughton, W. S.; Karimabadi, H.; Li, H.; Gary, S. P.; Guo, F.

    2013-12-01

    Observations of reconnection events at the Earth's magnetopause and in the solar wind show that reconnection occurs for a large range in magnetic shear angles extending to the very low shear limit 1. Here we report a fully kinetic study of the influence of the magnetic shear on details of reconnection such as its structure and rate. In previous work, we found that the electron diffusion region bifurcates into two or more distinct layers in regimes with weak magnetic shear2, a new feature that may be observable by NASA's up-coming Magnetospheric Multiscale mission. In this work, we have systematically extended the study to lower shear cases and found a new regime, where the reconnection electric field becomes much smaller and the properties of the reconnection changes significantly. We will discuss the role of various physics mechanisms in determining the observed scaling of the reconnection rate, including the dispersive properties of the waves in the system, the dissipation mechanisms and the tearing instability. 1 J. T. Goslings and T. D. Phan. APJL 763, L39, 2013 2 Yi-Hsin Liu et al. Phys. Rev. Lett. 110 , 265004, 2013

  15. Elastin-like recombinamers with acquired functionalities for gene-delivery applications.

    PubMed

    Piña, Maria J; Alex, Susan M; Arias, Francisco J; Santos, Mercedes; Rodriguez-Cabello, Jose C; Ramesan, Rekha M; Sharma, Chandra P

    2015-10-01

    In this work, well-defined elastin-like recombinamers (ELRs) were studied as a choice to the existing nonviral vectors due to their biocompatibility and ease of scale-up. Functional motifs, namely penetratin and LAEL fusogenic peptides were incorporated into a basic ELR sequence, and imidazole groups were subsequently covalently bound obtaining ELRs with new functionalities. Stable polyplexes composed of plasmid DNA and ELRs were formed. A particle size around 200 nm and a zeta potential up to nearly +24 mV made them suitable for gene delivery purposes. Additionally, viability and transfection assays with C6 rat glioma cell line showed an increase in the cellular uptake and transfection levels for the construction containing the LAEL motif. This study highlights the importance of controlling the polymer functionality using recombinant techniques and establishes the utility of ELRs as biocompatible nonviral systems for gene-therapy applications.

  16. How Toddlers Acquire and Transfer Tool Knowledge: Developmental Changes and the Role of Executive Functions

    ERIC Educational Resources Information Center

    Pauen, Sabina; Bechtel-Kuehne, Sabrina

    2016-01-01

    This report investigates tool learning and its relations to executive functions (EFs) in toddlers. In Study 1 (N = 93), 18-, 20-, 22-, and 24-month-old children learned equally well to choose a correct tool from observation, whereas performance based on feedback improved with age. Knowledge transfer showed significant progress after 22 months of…

  17. A function of the magnetocaloric effect in a magnetic fluid

    SciTech Connect

    Polunin, V.M.

    1986-01-01

    This paper examines a plane-parallel layer of magnetic fluid (MF) contacting the tmosphere. A relation which determines the density of the fluid with respect to the magnetic field strength is presented in the case of isothermal magnetization. The magnetocaloric effect is discussed which performs the function of one of the possible mechanisms of electromagnitic excitation of elastic vibrations in the MF. Two other mechanisms are discussed: magnetostriction and dipole-dipole.

  18. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    NASA Astrophysics Data System (ADS)

    Nan, Alexandrina; Bunge, Alexander; Turcu, Rodica

    2015-12-01

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  19. Wave functions of elliptical quantum dots in a magnetic field

    NASA Astrophysics Data System (ADS)

    Zhou, Daming; Lorke, Axel

    2015-03-01

    We use the variational principle to obtain the wave functions of elliptical quantum dots under the influence of an external magnetic field. For the first excited states, whose wave functions have recently been mapped experimentally, we find a simple expression, based on a linear combination of the wave functions in the absence of a magnetic field. The results illustrate how a magnetic field breaks the x-y symmetry and mixes the corresponding eigenstates. The obtained eigenenergies agree well with those obtained by more involved analytical and numerical methods.

  20. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    SciTech Connect

    Nan, Alexandrina Bunge, Alexander; Turcu, Rodica

    2015-12-23

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  1. Production and function of cytokines in natural and acquired immunity to Candida albicans infection.

    PubMed Central

    Ashman, R B; Papadimitriou, J M

    1995-01-01

    Host resistance against infections caused by the yeast Candida albicans is mediated predominantly by polymorphonuclear leukocytes and macrophages. Antigens of Candida stimulate lymphocyte proliferation and cytokine synthesis, and in both humans and mice, these cytokines enhance the candidacidal functions of the phagocytic cells. In systemic candidiasis in mice, cytokine production has been found to be a function of the CD4+ T helper (Th) cells. The Th1 subset of these cells, characterized by the production of gamma interferon and interleukin-2, is associated with macrophage activation and enhanced resistance against reinfection, whereas the Th2 subset, which produces interleukins-4, -6, and -10, is linked to the development of chronic disease. However, other models have generated divergent data. Mucosal infection generally elicits Th1-type cytokine responses and protection from systemic challenge, and identification of cytokine mRNA present in infected tissues of mice that develop mild or severe lesions does not show pure Th1- or Th2-type responses. Furthermore, antigens of C. albicans, mannan in particular, can induce suppressor cells that modulate both specific and nonspecific cellular and humoral immune responses, and there is an emerging body of evidence that molecular mimicry may affect the efficiency of anti-Candida responses within defined genetic contexts. PMID:8531890

  2. Pneumocystis colonization, airway inflammation, and pulmonary function decline in acquired immunodeficiency syndrome.

    PubMed

    Norris, Karen A; Morris, Alison; Patil, Sangita; Fernandes, Eustace

    2006-01-01

    As a result of improved diagnosis, treatment, and supportive care for HIV-infected patients, AIDS in developed countries has now become a chronic infection with prolonged survival time, but longterm complications are increasing contributors to morbidity and mortality. HIV-infected patients are at increased risk for the development of pulmonary complications, including chronic obstructive pulmonary disease (COPD); however, the mechanisms associated with this increased susceptibility have not been defined. Infectious agents may contribute to the development of COPD by upregulating inflammatory mediators in the lung that act in concert with cigarette smoke to promote lung pathology. Studies in human subjects and non-human primate models of AIDS suggest that the inflammatory response to asymptomatic carriage or colonization by the opportunistic pathogen, Pneumocystis sp. (Pc), is similar to that of COPD, which is characterized by influx of CD8+ T cells, neutrophils, and macrophages into the lungs. We have shown a high frequency of Pc colonization among asymptomatic HIV-infected subjects and in non-HIV infected subjects with COPD. To investigate the role of Pc in the progression of obstructive lung disease in HIV infections, we developed a non-human primate model of Pc colonizatoin and infection in simian immunodeficiency virus (SIV)-infected macaques. These animals develop a prolonged colonization state characterized by a persistent influx of CD8+ T cells and neutrophils, and local increases in IL-8, IFN-gamma, and TNF-alpha. SIV-infected Pc-colonized monkeys show progressive decline in pulmonary function compared to SIV-infected monkeys. We hypothesize that in the context of AIDS-immune dysfunction, Pc colonization induces inflammatory responses leading to changes in pulmonary function and architecture similar to that seen in emphysema. Information gained from these studies will lead to the development of interventions to prevent lung injury associated with Pc

  3. [Study of the pre- and post-treatment functionality of unilateral acquired brain injuries].

    PubMed

    Huertas-Hoyas, Elisabet; Pedrero-Pérez, Eduardo J; Águila-Maturana, Ana M; González-Alted, Carlos

    2014-04-16

    Introduccion. La mayoria de las personas que han sobrevivido a un daño cerebral lateralizado presenta secuelas que afectan a componentes sensoriomotores, cognitivos o conductuales. Estos deficits repercuten en la correcta ejecucion de actividades de la vida diaria, antes y despues de un tratamiento multidisciplinar. El objetivo de este estudio es analizar y comparar el perfil ocupacional de las personas con daño cerebral adquirido unilateral, tanto en personas con traumatismo craneoencefalico (TCE) como accidentes cerebrovasculares (ACV), mediante la independencia funcional, la capacidad, la participacion y la calidad del desempeño de las actividades cotidianas. Pacientes y metodos. Diseño cuasi experimental de cohortes con medidas transversales pre y postratamiento con una muestra de 58 personas, 28 con TCE y 30 con ACV, en ambos casos lateralizados. Las medidas utilizadas fueron la Functional Independence Measure + Functional Assessment Measure, la clasificacion internacional del funcionamiento, la discapacidad y la salud, y el Assessment of Motor and Process Skills. Resultados. Teniendo en cuenta los grupos analizados (muestra completa lateralizada, muestra por diagnostico), los resultados del analisis apuntan hacia la existencia de diferencias significativas y un moderado tamaño del efecto en las dos estimaciones transversales, otorgando mayores niveles de independencia a las lesiones sobrevenidas en el hemisferio derecho (p < 0,001). Sin embargo, al dividir la muestra segun el diagnostico, no aparecen diferencias significativas, salvo en las habilidades motoras, donde se muestran mayores puntuaciones en los TCE (p < 0,05). Conclusiones. Se piensa que lo que justifica las diferencias no es la modalidad de la lesion (TCE o ACV), sino la localizacion hemisferica. Por ello, se sugiere que las personas con daño cerebral adquirido en el hemisferio izquierdo requeriran una intervencion mas intensa.

  4. I kappa B kinase alpha (IKKα) activity is required for functional maturation of dendritic cells and acquired immunity to infection.

    PubMed

    Mancino, Alessandra; Habbeddine, Mohamed; Johnson, Ella; Luron, Lionel; Bebien, Magali; Memet, Sylvie; Fong, Carol; Bajenoff, Marc; Wu, Xuefeng; Karin, Michael; Caamano, Jorge; Chi, Hongbo; Seed, Michael; Lawrence, Toby

    2013-03-20

    Dendritic cells (DC) are required for priming antigen-specific T cells and acquired immunity to many important human pathogens, including Mycobacteriuim tuberculosis (TB) and influenza. However, inappropriate priming of auto-reactive T cells is linked with autoimmune disease. Understanding the molecular mechanisms that regulate the priming and activation of naïve T cells is critical for development of new improved vaccines and understanding the pathogenesis of autoimmune diseases. The serine/threonine kinase IKKα (CHUK) has previously been shown to have anti-inflammatory activity and inhibit innate immunity. Here, we show that IKKα is required in DC for priming antigen-specific T cells and acquired immunity to the human pathogen Listeria monocytogenes. We describe a new role for IKKα in regulation of IRF3 activity and the functional maturation of DC. This presents a unique role for IKKα in dampening inflammation while simultaneously promoting adaptive immunity that could have important implications for the development of new vaccine adjuvants and treatment of autoimmune diseases.

  5. Functional magnetic resonance imaging of internet addiction in young adults

    PubMed Central

    Sepede, Gianna; Tavino, Margherita; Santacroce, Rita; Fiori, Federica; Salerno, Rosa Maria; Di Giannantonio, Massimo

    2016-01-01

    AIM: To report the results of functional magnetic resonance imaging (fMRI) studies pertaining internet addiction disorder (IAD) in young adults. METHODS: We conducted a systematic review on PubMed, focusing our attention on fMRI studies involving adult IAD patients, free from any comorbid psychiatric condition. The following search words were used, both alone and in combination: fMRI, internet addiction, internet dependence, functional neuroimaging. The search was conducted on April 20th, 2015 and yielded 58 records. Inclusion criteria were the following: Articles written in English, patients’ age ≥ 18 years, patients affected by IAD, studies providing fMRI results during resting state or cognitive/emotional paradigms. Structural MRI studies, functional imaging techniques other than fMRI, studies involving adolescents, patients with comorbid psychiatric, neurological or medical conditions were excluded. By reading titles and abstracts, we excluded 30 records. By reading the full texts of the 28 remaining articles, we identified 18 papers meeting our inclusion criteria and therefore included in the qualitative synthesis. RESULTS: We found 18 studies fulfilling our inclusion criteria, 17 of them conducted in Asia, and including a total number of 666 tested subjects. The included studies reported data acquired during resting state or different paradigms, such as cue-reactivity, guessing or cognitive control tasks. The enrolled patients were usually males (95.4%) and very young (21-25 years). The most represented IAD subtype, reported in more than 85% of patients, was the internet gaming disorder, or videogame addiction. In the resting state studies, the more relevant abnormalities were localized in the superior temporal gyrus, limbic, medial frontal and parietal regions. When analyzing the task related fmri studies, we found that less than half of the papers reported behavioral differences between patients and normal controls, but all of them found significant

  6. Analysis of a 3-D system function measured for magnetic particle imaging.

    PubMed

    Rahmer, Jürgen; Weizenecker, Jürgen; Gleich, Bernhard; Borgert, Jörn

    2012-06-01

    Magnetic particle imaging (MPI) is a new tomographic imaging approach that can quantitatively map magnetic nanoparticle distributions in vivo. It is capable of volumetric real-time imaging at particle concentrations low enough to enable clinical applications. For image reconstruction in 3-D MPI, a system function (SF) is used, which describes the relation between the acquired MPI signal and the spatial origin of the signal. The SF depends on the instrumental configuration, the applied field sequence, and the magnetic particle characteristics. Its properties reflect the quality of the spatial encoding process. This work presents a detailed analysis of a measured SF to give experimental evidence that 3-D MPI encodes information using a set of 3-D spatial patterns or basis functions that is stored in the SF. This resembles filling 3-D k-space in magnetic resonance imaging, but is faster since all information is gathered simultaneously over a broad acquisition bandwidth. A frequency domain analysis shows that the finest structures that can be encoded with the presented SF are as small as 0.6 mm. SF simulations are performed to demonstrate that larger particle cores extend the set of basis functions towards higher resolution and that the experimentally observed spatial patterns require the existence of particles with core sizes of about 30 nm in the calibration sample. A simple formula is presented that qualitatively describes the basis functions to be expected at a certain frequency.

  7. Amine-functionalized magnetic mesoporous silica nanoparticles for DNA separation

    NASA Astrophysics Data System (ADS)

    Sheng, Wei; Wei, Wei; Li, Junjian; Qi, Xiaoliang; Zuo, Gancheng; Chen, Qi; Pan, Xihao; Dong, Wei

    2016-11-01

    We report a modified approach for the functionalized magnetic mesoporous silica nanoparticles (MMSN) using polymer microspheres incorporated with magnetic nanoparticles in the presence of cetyltrimethylammonium bromide (CTAB) and the core-shell magnetic silica nanoparticles (MSN). These particles were functionalized with amino groups via the addition of aminosilane directly to the particle sol. We then evaluate their DNA separation abilities and find the capacity of DNA binding significantly increased (210.22 μg/mg) compared with normal magnetic silica spheres (138.44 μg/mg) by using an ultraviolet and visible spectrophotometer (UV). The morphologies, magnetic properties, particle size, pore size, core-shell structure and Zeta potential are characterized by Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM), Powder X-ray diffraction (XRD), and dynamic light scattering (DLS). This work demonstrates that our MMSN own an excellent potential application in bioseparation and drug delivery.

  8. Controlling transport and chemical functionality of magnetic nanoparticles.

    PubMed

    Latham, Andrew H; Williams, Mary Elizabeth

    2008-03-01

    A wide range of metal, magnetic, semiconductor, and polymer nanoparticles with tunable sizes and properties can be synthesized by wet-chemical techniques. Magnetic nanoparticles are particularly attractive because their inherent superparamagnetic properties make them desirable for medical imaging, magnetic field assisted transport, and separations and analyses. With such applications on the horizon, synthetic routes for quickly and reliably rendering magnetic nanoparticle surfaces chemically functional have become an increasingly important focus. This Account describes common synthetic routes for making and functionalizing magnetic nanoparticles and discusses initial applications in magnetic field induced separations. The most widely studied magnetic nanoparticles are iron oxide (Fe2O3 and Fe3O4), cobalt ferrite (CoFe 2O4), iron platinum (FePt), and manganese ferrite (MnFe 2O4), although others have been investigated. Magnetic nanoparticles are typically prepared under either high-temperature organic phase or aqueous conditions, producing particles with surfaces that are stabilized by attached surfactants or associated ions. Although it requires more specialized glassware, high-temperature routes are generally preferred when a high degree of stability and low particle size dispersity is desired. Particles can be further modified with a secondary metal or polymer to create core-shell structures. The outer shells function as protective layers for the inner metal cores and alter the surface chemistry to enable postsynthetic modification of the surfactant chemistry. Efforts by our group as well as others have centered on pathways to yield nanoparticles with surfaces that are both easily functionalized and tunable in terms of the number and variety of attached species. Ligand place-exchange reactions have been shown quite successful for exchanging silanes, acids, thiols, and dopamine ligands onto the surfaces of some magnetic particles. Poly(ethylene oxide

  9. Magnetic Resonance, Functional (fMRI) -- Brain

    MedlinePlus

    ... thought, speech, movement and sensation, which is called brain mapping. help assess the effects of stroke, trauma or degenerative disease (such as Alzheimer's) on brain function. monitor the growth and function of brain ...

  10. Antiretroviral treatment initiation does not differentially alter neurocognitive functioning over time in youth with behaviorally acquired HIV.

    PubMed

    Nichols, Sharon L; Bethel, James; Kapogiannis, Bill G; Li, Tiandong; Woods, Steven P; Patton, E Doyle; Ren, Weijia; Thornton, Sarah E; Major-Wilson, Hanna O; Puga, Ana M; Sleasman, John W; Rudy, Bret J; Wilson, Craig M; Garvie, Patricia A

    2016-04-01

    Although youth living with behaviorally acquired HIV (YLWH) are at risk for cognitive impairments, the relationship of impairments to HIV and potential to improve with antiretroviral therapy (ART) are unclear. This prospective observational study was designed to examine the impact of initiation and timing of ART on neurocognitive functioning in YLWH in the Adolescent Medicine Trials Network for HIV/AIDS Interventions. Treatment naïve YLWH age 18-24 completed baseline and four additional assessments of attention/working memory, complex executive, and motor functioning over 3 years. Group 1 co-enrolled in an early ART initiation study and initiated ART at enrollment CD4 >350 (n = 56); group 2 had CD4 >350 and were not initiating ART (n = 66); group 3 initiated ART with CD4 <350 (n = 59) per standard of care treatment guidelines at the time. Treatment was de-intensified to boosted protease inhibitor monotherapy at 48 weeks for those in group 1 with suppressed viral load. Covariates included demographic, behavioral, and medical history variables. Analyses used hierarchical linear modeling. All groups showed improved performance with peak at 96 weeks in all three functional domains. Trajectories of change were not significantly associated with treatment, timing of treatment initiation, or ART de-intensification. Demographic variables and comorbidities were associated with baseline functioning but did not directly interact with change over time. In conclusion, YLWH showed improvement in neurocognitive functioning over time that may be related to practice effects and nonspecific impact of study participation. Neither improvement nor decline in functioning was associated with timing of ART initiation or therapy de-intensification.

  11. Computerised cognitive training in acquired brain injury: A systematic review of outcomes using the International Classification of Functioning (ICF).

    PubMed

    Sigmundsdottir, Linda; Longley, Wendy A; Tate, Robyn L

    2016-10-01

    Computerised cognitive training (CCT) is an increasingly popular intervention for people experiencing cognitive symptoms. This systematic review evaluated the evidence for CCT in adults with acquired brain injury (ABI), focusing on how outcome measures used reflect efficacy across components of the International Classification of Functioning, Disability and Health. Database searches were conducted of studies investigating CCT to treat cognitive symptoms in adult ABI. Scientific quality was rated using the PEDro-P and RoBiNT Scales. Ninety-six studies met the criteria. Most studies examined outcomes using measures of mental functions (93/96, 97%); fewer studies included measures of activities/participation (41/96, 43%) or body structures (8/96, 8%). Only 14 studies (15%) provided Level 1 evidence (randomised controlled trials with a PEDro-P score ≥ 6/10), with these studies suggesting strong evidence for CCT improving processing speed in multiple sclerosis (MS) and moderate evidence for improving memory in MS and brain tumour populations. There is a large body of research examining the efficacy of CCT, but relatively few Level 1 studies and evidence is largely limited to body function outcomes. The routine use of outcome measures of activities/participation would provide more meaningful evidence for the efficacy of CCT. The use of body structure outcome measures (e.g., neuroimaging) is a newly emerging area, with potential to increase understanding of mechanisms of action for CCT.

  12. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    PubMed Central

    2008-01-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed. PMID:21749733

  13. Acquired platelet function defect

    MedlinePlus

    ... Review Date 1/22/2015 Updated by: Rita Nanda, MD, Assistant Professor of Medicine, Section of Hematology/ ... constitute endorsements of those other sites. Copyright 1997-2017, A.D.A.M., Inc. Duplication for commercial ...

  14. Cyclosporine restores hematopoietic function by compensating for decreased Tregs in patients with pure red cell aplasia and acquired aplastic anemia.

    PubMed

    Dao, An T T; Yamazaki, Hirohito; Takamatsu, Hiroyuki; Sugimori, Chiharu; Katagiri, Takamasa; Maruyama, Hiroyuki; Zaimoku, Yoshitaka; Maruyama, Kana; Ly, Trung Q; Espinoza, Luis; Nakao, Shinji

    2016-04-01

    Most patients with acquired pure red cell aplasia (PRCA) and some with acquired aplastic anemia (AA) respond well to cyclosporine (CsA), but thereafter often show CsA dependency. The mechanism underlying this dependency remains unknown. We established a reliable method for measuring the regulatory T cell (Treg) count using FoxP3 and Helios expression as markers and determined the balance between Tregs and other helper T cell subsets in 16 PRCA and 29 AA patients. The ratios of interferon-γ-producing CD4(+) (Th1) T cells to Tregs in untreated patients and CsA-dependent patients were significantly higher (PRCA 5.77 ± 1.47 and 7.38 ± 2.58; AA 6.18 ± 2.35 and 8.94 ± 4.06) than in healthy volunteers (HVs; 3.33 ± 0.90) due to the profound decrease in the percentage of Tregs. In contrast, the ratios were comparable to HVs in convalescent CsA-treated AA patients (4.74 ± 2.10) and AA patients in remission after the cessation of CsA treatment (4.24 ± 1.67). Low-dose CsA (100 ng/ml) inhibited the proliferation of conventional T cells (Tconv) to a similar degree to the inhibition by Tregs in a co-culture with a 1:1 Treg/Tconv ratio. The data suggest that CsA may reverse the hematopoietic suppression in PRCA and AA patients by compensating for the inadequate immune regulatory function that occurs due to a profound decrease in the Treg count.

  15. Correlation Functions of the Magnetization in Thin Films

    NASA Astrophysics Data System (ADS)

    Rebei, A.; Simionato, M.; Parker, G. J.

    2003-05-01

    We calculate the correlation functions of uniform magnetization in thin ferromagnetic films for small deviations from equilibrium, by using a functional formalism. To take account of dissipation and fluctuations consistently, the magnetization is coupled to a bosonic heat bath. The correlation functions show strong dependence on the nature of the coupling between the bath and the system. Depending on what coupling we choose, we show how the recent results $(\\text{J. Appl. Phys. 90, 5768 (2001); Phys. Rev. B 65, 172417 (2002)}) $ obtained by macroscopic methods can be related to the microscopic treatment adopted here.

  16. A de novo loss-of-function GRIN2A mutation associated with childhood focal epilepsy and acquired epileptic aphasia

    PubMed Central

    Zhang, Yujia; Kusumoto, Hirofumi; Zhang, Jin; Chen, Wenjuan; XiangWei, Wenshu; Shaulsky, Gil H.; Hu, Chun; Traynelis, Stephen F.; Yuan, Hongjie; Jiang, Yuwu

    2017-01-01

    Objective N-methyl-D-aspartate receptors (NMDAR) subunit GRIN2A/GluN2A mutations have been identified in patients with various neurological diseases, such as epilepsy and intellectual disability / developmental delay (ID/DD). In this study, we investigated the phenotype and underlying molecular mechanism of a GRIN2A missense mutation identified by next generation sequencing on idiopathic focal epilepsy using in vitro electrophysiology. Methods Genomic DNA of patients with epilepsy and ID/DD were sequenced by targeted next-generation sequencing within 300 genes related to epilepsy and ID/DD. The effects of one missense GRIN2A mutation on NMDAR function were evaluated by two-electrode voltage clamp current recordings and whole cell voltage clamp current recordings. Results We identified one de novo missense GRIN2A mutation (Asp731Asn, GluN2A(D731N)) in a child with unexplained epilepsy and DD. The D731N mutation is located in a portion of the agonist-binding domain (ABD) in the GluN2A subunit, which is the binding pocket for agonist glutamate. This residue in the ABD is conserved among vertebrate species and all other NMDAR subunits, suggesting an important role in receptor function. The proband shows developmental delay as well as EEG-confirmed seizure activity. Functional analyses reveal that the GluN2A(D731N) mutation decreases glutamate potency by over 3,000-fold, reduces amplitude of current response, shortens synaptic-like response time course, and decreases channel open probability, while enhancing sensitivity to negative allosteric modulators, including extracellular proton and zinc inhibition. The combined effects reduce NMDAR function. Significance We identified a de novo missense mutation in the GRIN2A gene in a patient with childhood focal epilepsy and acquired epileptic aphasia. The mutant decreases NMDAR activation suggesting NMDAR hypofunction may contribute to the epilepsy pathogenesis. PMID:28182669

  17. Functionalization of polydopamine coated magnetic nanoparticles with biological entities

    NASA Astrophysics Data System (ADS)

    Mǎgeruşan, Lidia; Mrówczyński, Radosław; Turcu, Rodica

    2015-12-01

    New hybrid materials, obtained through introduction of cysteine, lysine and folic acid as biological entities into polydopamine-coated magnetite nanoparticles, are reported. The syntheses are straight forward and various methods were applied for structural and morphological characterization of the resulting nanoparticles. XPS proved a very powerful tool for surface chemical analysis and it evidences the functionalization of polydopamine coated magnetite nanoparticles. The superparamagnetic behavior and the high values of saturation magnetization recommend all products for further application where magnetism is important for targeting, separation, or heating by alternative magnetic fields.

  18. Electron Cloud Trapping in Recycler Combined Function Dipole Magnets

    SciTech Connect

    Antipov, Sergey A.; Nagaitsev, S.

    2016-10-04

    Electron cloud can lead to a fast instability in intense proton and positron beams in circular accelerators. In the Fermilab Recycler the electron cloud is confined within its combined function magnets. We show that the field of combined function magnets traps the electron cloud, present the results of analytical estimates of trapping, and compare them to numerical simulations of electron cloud formation. The electron cloud is located at the beam center and up to 1% of the particles can be trapped by the magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multiturn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The multi-turn build-up can be stopped by injection of a clearing bunch of 1010 p at any position in the ring.

  19. Functional cliques in the amygdala and related brain networks driven by fear assessment acquired during movie viewing.

    PubMed

    Kinreich, Sivan; Intrator, Nathan; Hendler, Talma

    2011-01-01

    One of the greatest challenges involved in studying the brain mechanisms of fear is capturing the individual's unique instantaneous experience. Brain imaging studies to date commonly sacrifice valuable information regarding the individual real-time conscious experience, especially when focusing on elucidating the amygdala's activity. Here, we assumed that by using a minimally intrusive cue along with applying a robust clustering approach to probe the amygdala, it would be possible to rate fear in real time and to derive the related network of activation. During functional magnetic resonance imaging scanning, healthy volunteers viewed two excerpts from horror movies and were periodically auditory cued to rate their instantaneous experience of "I'm scared." Using graph theory and community mathematical concepts, data-driven clustering of the fear-related functional cliques in the amygdala was performed guided by the individually marked periods of heightened fear. Individually tailored functions derived from these amygdala activation cliques were subsequently applied as general linear model predictors to a whole-brain analysis to reveal the correlated networks. Our results suggest that by using a localized robust clustering approach, it is possible to probe activation in the right dorsal amygdala that is directly related to individual real-time emotional experience. Moreover, this fear-evoked amygdala revealed two opposing networks of co-activation and co-deactivation, which correspond to vigilance and rest-related circuits, respectively.

  20. Effect of Skin-To-Skin Contact on Preterm Infant Skin Barrier Function and Hospital-Acquired Infection

    PubMed Central

    Abouelfettoh, Amel; Ludington-Hoe, Susan M.; Burant, Chris J.; Visscher, Marty O.

    2011-01-01

    Background The preterm infants' skin is structurally and functionally immature at birth because of immature stratum corneum barrier function, leading to problems with fluid loses, thermoregulation, and infection. Two parameters of barrier function can be non-invasively assessed: Stratum Corneum Hydration (SCH) and Transepidermal Water Loss (TEWL). Skin-to-Skin Care (SSC) is the proposed independent variable that might affect barrier function by decreasing TEWL and increasing SCH, thereby improving stratum corneum barrier function and consequently decreasing the rate of infection. No study of SSC's effects on TEWL and SCH of preterm infants could be found. The purpose of the study was to determine the effect of 5 daily Skin-to-Skin Contact sessions on infant skin hydration (SCH), transepidermal evaporated water loss (TEWL), and on SCH when TEWL was controlled, and on the presence of hospital acquired infection. Methods A one-group pretest-test-posttest design with 10 preterm infants (28 - 30 wks GA < 32 wks postmenstrual age, and no infection at entry). Test = 90 minutes of SSC; pre-test and post-test = 30 minutes each of prone positioning in an incubator. SCH and TEWL were taken on Days 1 and 5 at the beginning, middle and end of each period using Multi-Probe Adaptor. A 3 X 3 X 2 Repeated Measures Mixed Models Design, including a covariate, was used to analyze level of Skin Hydration. Specifically, the model tested comparisons in SCH made across repetitions, time, and days, as well as all possible interactions while controlling for TEWL. Descriptive statistics described the number of positive blood cultures during hospitalization and the presence of infections four weeks post-discharge. Results Significant differences in skin hydration were found across TIME (Pre-SSC, SSC, Post-SSC) (F = 21.86; p < 0.001). One infant had a positive blood culture during hospitalization; no infants had signs of infection by 4 weeks post-discharge. Conclusions The study has begun

  1. Surface functionalized biocompatible magnetic nanospheres for cancer hyperthermia.

    SciTech Connect

    Liu, X.; Novosad, V.; Rozhkova, E. A.; Chen, H.; Yefremenko, V.; Pearson, J.; Torno, M.; Bader, S. D.; Rosengart, A. J.; Univ. Chicago Pritzker School of Medicine

    2007-06-01

    We report a simplified single emulsion (oil-in-water) solvent evaporation protocol to synthesize surface functionalized biocompatible magnetic nanospheres by using highly concentrated hydrophobic magnetite (gel) and a mixture of poly(D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol-maleimide) (PLA-PEG-maleimide) (10:1 by mass) polymers. The as-synthesized particles are approximately spherical with an average diameter of 360-370 nm with polydispersity index of 0.12-0.18, are surface-functionalized with maleimide groups, and have saturation magnetization values of 25-40 emu/g. The efficiency of the heating induced by 400-kHz oscillating magnetic fields is compared for two samples with different magnetite loadings. Results show that these nanospheres have the potential to provide an efficient cancer-targeted hyperthermia.

  2. Peptide-functionalized magnetic nanoparticles for cancer therapy applications

    NASA Astrophysics Data System (ADS)

    Hauser, Anastasia Kruse

    Lung cancer is one of the leading causes of cancer deaths in the United States. Radiation and chemotherapy are conventional treatments, but they result in serious side effects and the probability of tumor recurrence remains high. Therefore, there is an increasing need to enhance the efficacy of conventional treatments. Magnetic nanoparticles have been previously studied for a variety of applications such as magnetic resonance imaging contrast agents, anemia treatment, magnetic cell sorting and magnetically mediated hyperthermia (MMH). In this work, dextran coated iron oxide nanoparticles were developed and functionalized with peptides to target the nanoparticles to either the extracellular matrix (ECM) of tumor tissue or to localize the nanoparticles in subcellular regions after cell uptake. The magnetic nanoparticles were utilized for a variety of applications. First, heating properties of the nanoparticles were utilized to administer hyperthermia treatments combined with chemotherapy. The nanoparticles were functionalized with peptides to target fibrinogen in the ECM and extensively characterized for their physicochemical properties, and MMH combined with chemotherapy was able to enhance the toxicity of chemotherapy. The second application of the nanoparticles was magnetically mediated energy delivery. This treatment does not result in a bulk temperature rise upon actuation of the nanoparticles by an alternating magnetic field (AMF) but rather results in intracellular damage via friction from Brownian rotation or nanoscale heating effects from Neel relaxations. The nanoparticles were functionalized with a cell penetrating peptide to facilitate cell uptake and lysosomal escape. The intracellular effects of the internalized nanoparticles alone and with activation by an AMF were evaluated. Iron concentrations in vivo are highly regulated as excess iron can catalyze the formation of the hydroxyl radical through Fenton chemistry. Although often a concern of using iron

  3. Functional Connectivity Magnetic Resonance Imaging Classification of Autism

    ERIC Educational Resources Information Center

    Anderson, Jeffrey S.; Nielsen, Jared A.; Froehlich, Alyson L.; DuBray, Molly B.; Druzgal, T. Jason; Cariello, Annahir N.; Cooperrider, Jason R.; Zielinski, Brandon A.; Ravichandran, Caitlin; Fletcher, P. Thomas; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

    2011-01-01

    Group differences in resting state functional magnetic resonance imaging connectivity between individuals with autism and typically developing controls have been widely replicated for a small number of discrete brain regions, yet the whole-brain distribution of connectivity abnormalities in autism is not well characterized. It is also unclear…

  4. Utp14b: a unique retrogene within a gene that has acquired multiple promoters and a specific function in spermatogenesis.

    PubMed

    Zhao, Ming; Rohozinski, Jan; Sharma, Manju; Ju, Jun; Braun, Robert E; Bishop, Colin E; Meistrich, Marvin L

    2007-04-15

    The mouse retrogene Utp14b is essential for male fertility, and a mutation in its sequence results in the sterile juvenile spermatogonial depletion (jsd) phenotype. It is a retrotransposed copy of the Utp14a gene, which is located on the X chromosome, and is inserted within an intron of the autosomal acyl-CoA synthetase long-chain family member 3 (Acsl3) gene. To elucidate the roles of the Utp14 genes in normal spermatogenic cell development as a basis for understanding the defects that result in the jsd phenotype, we analyzed the various mRNAs produced from the Utp14b retrogene and their expression in different cell types. Two classes of transcripts were identified: variant 1, a transcript driven by the host gene promoter, that is predominantly found in germ cells but is ubiquitously expressed at low levels; and variants 2-5, a group of alternatively spliced transcripts containing some unique untranslated exons that are transcribed from a novel promoter that is germ-cell-specific. Utp14b (predominantly variant 1) is expressed at moderately high levels in pachytene spermatocytes, the developmental stage at which the expression of the X-linked Utp14a is suppressed. The levels of both classes of Utp14b transcripts were highest in round spermatids despite the transcription of Utp14a in these cells. We propose that when Utp14b initially inserted into Acsl3, it utilized the Acsl3 promoter to drive expression in pachytene spermatocytes to compensate for inactivation of Utp14a expression. The novel cell-type-specific promoter for Utp14b likely evolved later, as the protein may have acquired a germ cell-specific function in spermatid development.

  5. Acquired hyperpigmentations*

    PubMed Central

    Cestari, Tania Ferreira; Dantas, Lia Pinheiro; Boza, Juliana Catucci

    2014-01-01

    Cutaneous hyperpigmentations are frequent complaints, motivating around 8.5% of all dermatological consultations in our country. They can be congenital, with different patterns of inheritance, or acquired in consequence of skin problems, systemic diseases or secondary to environmental factors. The vast majority of them are linked to alterations on the pigment melanin, induced by different mechanisms. This review will focus on the major acquired hyperpigmentations associated with increased melanin, reviewing their mechanisms of action and possible preventive measures. Particularly prominent aspects of diagnosis and therapy will be emphasized, with focus on melasma, post-inflammatory hyperpigmentation, periorbital pigmentation, dermatosis papulosa nigra, phytophotodermatoses, flagellate dermatosis, erythema dyschromicum perstans, cervical poikiloderma (Poikiloderma of Civatte), acanthosis nigricans, cutaneous amyloidosis and reticulated confluent dermatitis PMID:24626644

  6. Room temperature organic magnets derived from sp3 functionalized graphene

    PubMed Central

    Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B.; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

    2017-01-01

    Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp2-conjugated diradical motifs embedded in an sp3 matrix and superexchange interactions via –OH functionalization. PMID:28216636

  7. Room temperature organic magnets derived from sp(3) functionalized graphene.

    PubMed

    Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

    2017-02-20

    Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp(3) coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp(2)-conjugated diradical motifs embedded in an sp(3) matrix and superexchange interactions via -OH functionalization.

  8. Room temperature organic magnets derived from sp3 functionalized graphene

    NASA Astrophysics Data System (ADS)

    Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B.; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

    2017-02-01

    Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp2-conjugated diradical motifs embedded in an sp3 matrix and superexchange interactions via -OH functionalization.

  9. Functional orthopedic magnetic appliance (FOMA) II--modus operandi.

    PubMed

    Vardimon, A D; Stutzmann, J J; Graber, T M; Voss, L R; Petrovic, A G

    1989-05-01

    A new functional appliance (FA) to correct Class II dentoskeletal malocclusions is introduced. The functional orthopedic magnetic appliance (FOMA) II uses upper and lower attracting magnetic means (Nd2Fe14B) to constrain the lower jaw in an advanced sagittal posture. In vitro, a special gauge transducer measured the magnetic attractive path and forces. In vivo, 13 prepubertal female Macaca fascicularis monkeys received facial implants and were treated for 4 months with the following appliances: conventional FA (four subjects), FOMA II (five subjects), a combined FOMA II + FA (two subjects), and sham (control) appliance (two subjects). The in vitro results showed the following: vertico-sagitally displaced upper and lower magnets attracted ultimately along an oblique line with a terminal horizonal slide to become fully superimposed; the functional performance improved when the magnetic interface acted as a magnetic inclined plane; and the magnetic force was able to guide and constrain the mandible toward the constructive protrusive closure position (CPCP) (1.2 mm, F = 570 gm) from levels below the habitual rest position (3 mm, F = 219 gm) and the electromyographic (EMG) relaxed position (8.5 mm, F = 45 gm). The in vivo results demonstrated the following: functional performance increased in FOMA II (22%) and in the combined FOMA II + FA (28%) over the conventional FA; mandibular length increased significantly in the treated animals (means = 2.83 +/- 0.70 mm) over the control animals (means = 0.43 +/- 0.08 mm); incisor proclination was lower in magnetic appliances (means = 4.57 +/- 1.76 degrees) than in the conventional FA (means = 8.75 +/- 1.85 degrees); mandibular elongation and condylar posterior inclination resulted from posterosuperior endochondral growth (increased cell proliferation and/or hyperplasia of functional chondroblasts) and by bony remodeling of the condylar neck (apposition posterior border, resorption anterior border), respectively; virtually no

  10. Complex-number representation of informed basis functions in general linear modeling of Functional Magnetic Resonance Imaging.

    PubMed

    Wang, Pengwei; Wang, Zhishun; He, Lianghua

    2012-03-30

    Functional Magnetic Resonance Imaging (fMRI), measuring Blood Oxygen Level-Dependent (BOLD), is a widely used tool to reveal spatiotemporal pattern of neural activity in human brain. Standard analysis of fMRI data relies on a general linear model and the model is constructed by convolving the task stimuli with a hypothesized hemodynamic response function (HRF). To capture possible phase shifts in the observed BOLD response, the informed basis functions including canonical HRF and its temporal derivative, have been proposed to extend the hypothesized hemodynamic response in order to obtain a good fitting model. Different t contrasts are constructed from the estimated model parameters for detecting the neural activity between different task conditions. However, the estimated model parameters corresponding to the orthogonal basis functions have different physical meanings. It remains unclear how to combine the neural features detected by the two basis functions and construct t contrasts for further analyses. In this paper, we have proposed a novel method for representing multiple basis functions in complex domain to model the task-driven fMRI data. Using this method, we can treat each pair of model parameters, corresponding respectively to canonical HRF and its temporal derivative, as one complex number for each task condition. Using the specific rule we have defined, we can conveniently perform arithmetical operations on the estimated model parameters and generate different t contrasts. We validate this method using the fMRI data acquired from twenty-two healthy participants who underwent an auditory stimulation task.

  11. First results about recovery of walking function in patients with intensive care unit-acquired muscle weakness from the General Weakness Syndrome Therapy (GymNAST) cohort study

    PubMed Central

    Mehrholz, Jan; Mückel, Simone; Oehmichen, Frank; Pohl, Marcus

    2015-01-01

    Objectives To describe the time course of recovery of walking function and other activities of daily living in patients with intensive care unit (ICU)-acquired muscle weakness. Design This is a cohort study. Participants We included critically ill patients with ICU-acquired muscle weakness. Setting Post-acute ICU and rehabilitation units in Germany. Measures We measured walking function, muscle strength, activities in daily living, motor and cognitive function. Results We recruited 150 patients (30% female) who fulfilled our inclusion and exclusion criteria. The primary outcome recovery of walking function was achieved after a median of 28.5 days (IQR=45) after rehabilitation onset and after a median of 81.5 days (IQR=64) after onset of illness. Our final multivariate model for recovery of walking function included two clinical variables from baseline: the Functional Status Score ICU (adjusted HR=1.07 (95% CI 1.03 to 1.12) and the ability to reach forward in cm (adjusted HR=1.02 (95% CI 1.00 to 1.04). All secondary outcomes but not pain improved significantly in the first 8 weeks after study onset. Conclusions We found good recovery of walking function for most patients and described the recovery of walking function of people with ICU-acquired muscle weakness. Trials registrations number Sächsische Landesärztekammer EK-BR-32/13-1; DRKS00007181, German Register of Clinical Trials. PMID:26700274

  12. Functional magnetic resonance imaging in medicine and physiology

    SciTech Connect

    Moonen, C.T.W.; van Zijl, P.C.M.; Frank, J.A.; Bihan, D.L.; Becker, E.D. )

    1990-10-05

    Magnetic resonance imaging (MRI) is a well-established diagnostic tool that provides detailed information about macroscopic structure and anatomy. Recent advances in MRI allow the noninvasive spatial evaluation of various biophysical and biochemical processes in living systems. Specifically, the motion of water can be measured in processes such as vascular flow, capillary flow, diffusion, and exchange. In addition, the concentrations of various metabolites can be determined for the assessment of regional regulation of metabolism. Examples are given that demonstrate the use of functional MRI for clinical and research purposes. This development adds a new dimension to the application of magnetic resonance to medicine and physiology.

  13. Exponentially localized Wannier functions in periodic zero flux magnetic fields

    NASA Astrophysics Data System (ADS)

    De Nittis, G.; Lein, M.

    2011-11-01

    In this work, we investigate conditions which ensure the existence of an exponentially localized Wannier basis for a given periodic hamiltonian. We extend previous results [Panati, G., Ann. Henri Poincare 8, 995-1011 (2007), 10.1007/s00023-007-0326-8] to include periodic zero flux magnetic fields which is the setting also investigated by Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009), 10.1088/1751-8113/42/2/025203]. The new notion of magnetic symmetry plays a crucial rôle; to a large class of symmetries for a non-magnetic system, one can associate "magnetic" symmetries of the related magnetic system. Observing that the existence of an exponentially localized Wannier basis is equivalent to the triviality of the so-called Bloch bundle, a rank m hermitian vector bundle over the Brillouin zone, we prove that magnetic time-reversal symmetry is sufficient to ensure the triviality of the Bloch bundle in spatial dimension d = 1, 2, 3. For d = 4, an exponentially localized Wannier basis exists provided that the trace per unit volume of a suitable function of the Fermi projection vanishes. For d > 4 and d ⩽ 2m (stable rank regime) only the exponential localization of a subset of Wannier functions is shown; this improves part of the analysis of Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009), 10.1088/1751-8113/42/2/025203]. Finally, for d > 4 and d > 2m (unstable rank regime) we show that the mere analysis of Chern classes does not suffice in order to prove triviality and thus exponential localization.

  14. Functional orthopedic magnetic appliance (FOMA) III--modus operandi.

    PubMed

    Vardimon, A D; Graber, T M; Voss, L R; Muller, T P

    1990-02-01

    An intraoral intermaxillary appliance has been developed for the treatment of Class III malocclusions that exhibit midface sagittal deficiency with or without mandibular excess. The functional orthopedic magnetic appliance (FOMA) III consists of upper and lower acrylic plates with a permanent magnet incorporated into each plate. The upper magnet is linked to a retraction screw. The upper magnet is retracted periodically (e.g., monthly) to stimulate maxillary advancement and mandibular retardation. The attractive mode neodymium magnets used in this study produced a horizontal force of 98 gm and a vertical force of 371 gm. Six female Macaca fascicularis monkeys were treated with FOMA IIIs. An additional three animals were treated with sham appliances. After 4 months of treatment, the following results were found: the growth pattern of the cranial base (saddle angle) was not altered; midfacial protraction did occur along a recumbent hyperbolic curve with a horizontal maxillary displacement and an anterosuperior premaxillary rotation; the cumulative protraction of the maxillary complex was initiated at the pterygomaxillary fissure with an additional contribution provided by other circummaxillary sutures (zygomaticomaxillary s., transverse s., premaxillary s.); and inhibition of mandibular length was minimal, but a tendency toward a vertical condylar growth pattern was observed. The interaction between sutural and condylar growth sites appeared biphasic, characterized by an immediate and rapid excitation of the circummaxillary sutures followed by a delayed and slow suppression of the condylar cartilage. Long-term animal and clinical FOMA III studies are recommended.

  15. Hyperpolarized 3He functional magnetic resonance imaging of bronchoscopic airway bypass in chronic obstructive pulmonary disease

    PubMed Central

    Mathew, Lindsay; Kirby, Miranda; Farquhar, Donald; Licskai, Christopher; Santyr, Giles; Etemad-Rezai, Roya; Parraga, Grace; McCormack, David G

    2012-01-01

    A 73-year-old exsmoker with Global initiative for chronic Obstructive Lung Disease stage III chronic obstructive pulmonary disease underwent airway bypass (AB) as part of the Exhale Airway Stents for Emphysema (EASE) trial, and was the only EASE subject to undergo hyperpolarized 3He magnetic resonance imaging for evaluation of lung function pre- and post-AB. 3He magnetic resonance imaging was acquired twice previously (32 and eight months pre-AB) and twice post-AB (six and 12 months post-AB). Six months post-AB, his increase in forced vital capacity was <12% predicted, and he was classified as an AB nonresponder. However, post-AB, he also demonstrated improvements in quality of life scores, 6 min walk distance and improvements in 3He gas distribution in the regions of stent placement. Given the complex relationship between well-established pulmonary function and quality of life measurements, the present case provides evidence of the value-added information functional imaging may provide in chronic obstructive pulmonary disease interventional studies. PMID:22332133

  16. Hyperpolarized 3He functional magnetic resonance imaging of bronchoscopic airway bypass in chronic obstructive pulmonary disease.

    PubMed

    Mathew, Lindsay; Kirby, Miranda; Farquhar, Donald; Licskai, Christopher; Santyr, Giles; Etemad-Rezai, Roya; Parraga, Grace; McCormack, David G

    2012-01-01

    A 73-year-old exsmoker with Global initiative for chronic Obstructive Lung Disease stage III chronic obstructive pulmonary disease underwent airway bypass (AB) as part of the Exhale Airway Stents for Emphysema (EASE) trial, and was the only EASE subject to undergo hyperpolarized 3He magnetic resonance imaging for evaluation of lung function pre- and post-AB. 3He magnetic resonance imaging was acquired twice previously (32 and eight months pre-AB) and twice post-AB (six and 12 months post-AB). Six months post-AB, his increase in forced vital capacity was <12% predicted, and he was classified as an AB nonresponder. However, post-AB, he also demonstrated improvements in quality of life scores, 6 min walk distance and improvements in 3He gas distribution in the regions of stent placement. Given the complex relationship between well-established pulmonary function and quality of life measurements, the present case provides evidence of the value-added information functional imaging may provide in chronic obstructive pulmonary disease interventional studies.

  17. Methods for functional magnetic resonance imaging in normal and lesioned behaving monkeys.

    PubMed

    Pinsk, Mark A; Moore, Tirin; Richter, Marlene C; Gross, Charles G; Kastner, Sabine

    2005-04-30

    Methods for performing functional magnetic resonance imaging (fMRI) studies in behaving and lesioned monkeys using a human MR scanner are reported. Materials for head implant surgery were selected based on tests for magnetic susceptibility. A primate chair with a rigid head fixation system and a mock scanner environment for training were developed. To perform controlled visual studies, monkeys were trained to maintain fixation for several minutes using a novel training technique that utilized continuous juice rewards. A surface coil was used to acquire anatomical and functional images in four monkeys, one with a partial lesion of striate cortex. High-resolution anatomical images were used after non-uniform intensity correction to create cortical surface reconstructions of both lesioned and normal hemispheres. Our methods were confirmed in two visual experiments, in which functional activations were obtained during both free viewing and fixation conditions. In one experiment, face-selective activity was found in the fundus and banks of the superior temporal sulcus and the middle temporal gyrus in monkeys viewing pictures of faces and objects while maintaining fixation. In a second experiment, regions in occipital, parietal, and frontal cortex were activated in lesioned and normal animals viewing a cartoon movie. Importantly, in the animal with the striate lesion, fMRI signals were obtained in the immediate vicinity of the lesion. Our results extend those previously reported by providing a detailed account of the technique and by demonstrating the feasibility of fMRI in monkeys with lesions.

  18. Functional magnetic resonance imaging in oncology: state of the art.

    PubMed

    Guimaraes, Marcos Duarte; Schuch, Alice; Hochhegger, Bruno; Gross, Jefferson Luiz; Chojniak, Rubens; Marchiori, Edson

    2014-01-01

    In the investigation of tumors with conventional magnetic resonance imaging, both quantitative characteristics, such as size, edema, necrosis, and presence of metastases, and qualitative characteristics, such as contrast enhancement degree, are taken into consideration. However, changes in cell metabolism and tissue physiology which precede morphological changes cannot be detected by the conventional technique. The development of new magnetic resonance imaging techniques has enabled the functional assessment of the structures in order to obtain information on the different physiological processes of the tumor microenvironment, such as oxygenation levels, cellularity and vascularity. The detailed morphological study in association with the new functional imaging techniques allows for an appropriate approach to cancer patients, including the phases of diagnosis, staging, response evaluation and follow-up, with a positive impact on their quality of life and survival rate.

  19. Functional magnetic resonance imaging in oncology: state of the art*

    PubMed Central

    Guimaraes, Marcos Duarte; Schuch, Alice; Hochhegger, Bruno; Gross, Jefferson Luiz; Chojniak, Rubens; Marchiori, Edson

    2014-01-01

    In the investigation of tumors with conventional magnetic resonance imaging, both quantitative characteristics, such as size, edema, necrosis, and presence of metastases, and qualitative characteristics, such as contrast enhancement degree, are taken into consideration. However, changes in cell metabolism and tissue physiology which precede morphological changes cannot be detected by the conventional technique. The development of new magnetic resonance imaging techniques has enabled the functional assessment of the structures in order to obtain information on the different physiological processes of the tumor microenvironment, such as oxygenation levels, cellularity and vascularity. The detailed morphological study in association with the new functional imaging techniques allows for an appropriate approach to cancer patients, including the phases of diagnosis, staging, response evaluation and follow-up, with a positive impact on their quality of life and survival rate. PMID:25741058

  20. Functional magnetic resonance imaging reveals brain regions mediating the response to resistive expiratory loads in humans.

    PubMed Central

    Gozal, D; Omidvar, O; Kirlew, K A; Hathout, G M; Lufkin, R B; Harper, R M

    1996-01-01

    Obstructive lung disease is the most common form of respiratory disturbance. However, the location of brain structures underlying the ventilatory response to resistive expiratory loads is unknown in humans. To study this issue, midsagittal magnetic resonance images were acquired in eight healthy volunteers before and after application of a moderate resistive expiratory load (30 cmH2O/liter/s), using functional magnetic resonance imaging (fMRI) strategies (1.5-T magnetic resonance; repetition time: 72 ms; echo time: 45 ms; flip angle: 30 degrees; field of view: 26 cm; slice thickness: 5 mm; 128 x 256 x 1 number of excitations). Digital image subtractions and region of interest analyses revealed significant increases in fMRI signal intensity in discrete areas of the ventral medulla, ventral and dorsal pontomedullary structures, basal forebrain, and cerebellum. Upon load withdrawal, a rapid fMRI signal off-transient occurred in all activated sites. Application of an identical load immediately after recovery from the initial stimulus resulted in smaller signal increases (P < 0.02). Prolongation of load duration was associated with progressive fMRI signal decrease across activated regions. In three additional subjects, the threshold for significant MRI signal increases was established at expiratory loads > or = 15 cmH2O/liter/s and was dose dependent with increasing loads. We conclude that resistive expiratory loads > or = 15 cmH2O/liter/s elicit regional activation of discrete brain locations in humans. PMID:8550849

  1. MAGNETIC HELICITY SPECTRUM OF SOLAR WIND FLUCTUATIONS AS A FUNCTION OF THE ANGLE WITH RESPECT TO THE LOCAL MEAN MAGNETIC FIELD

    SciTech Connect

    Podesta, J. J.; Gary, S. P.

    2011-06-10

    Magnetic field data acquired by the Ulysses spacecraft in high-speed streams over the poles of the Sun are used to investigate the normalized magnetic helicity spectrum {sigma}{sub m} as a function of the angle {theta} between the local mean magnetic field and the flow direction of the solar wind. This spectrum provides important information about the constituent modes at the transition to kinetic scales that occurs near the spectral break separating the inertial range from the dissipation range. The energetically dominant signal at scales near the thermal proton gyroradius k{sub perpendicular{rho}i} {approx} 1 often covers a wide band of propagation angles centered about the perpendicular direction, {theta} {approx_equal} 90{sup 0} {+-} 30{sup 0}. This signal is consistent with a spectrum of obliquely propagating kinetic Alfven waves with k{sub perpendicular} >> k{sub ||} in which there is more energy in waves propagating away from the Sun and along the direction of the local mean magnetic field than toward the Sun. Moreover, this signal is principally responsible for the reduced magnetic helicity spectrum measured using Fourier transform techniques. The observations also reveal a subdominant population of nearly parallel propagating electromagnetic waves near the proton inertial scale k{sub ||} c/{omega}{sub pi} {approx} 1 that often exhibit high magnetic helicity |{sigma}{sub m}| {approx_equal} 1. These waves are believed to be caused by proton pressure anisotropy instabilities that regulate distribution functions in the collisionless solar wind. Because of the existence of a drift of alpha particles with respect to the protons, the proton temperature anisotropy instability that operates when T{sub pperpendicular}/T{sub p||} > 1 preferentially generates outward propagating ion-cyclotron waves and the fire-hose instability that operates when T{sub pperpendicular}/T{sub p||} < 1 preferentially generates inward propagating whistler waves. These kinetic processes

  2. Functional magnetic resonance imaging of the brain: a quick review.

    PubMed

    Vaghela, Viratsinh; Kesavadas, Chandrasekharan; Thomas, Bejoy

    2010-01-01

    Ability to non-invasively map the hemodynamic changes occurring focally in areas of brain involved in various motor, sensory and cognitive functions by functional magnetic resonance imaging (fMRI) has revolutionized research in neuroscience in the last two decades. This technique has already gained clinical use especially in pre-surgical evaluation of epilepsy and neurosurgical planning of resection of mass lesions adjacent to eloquent cortex. In this review we attempt to illustrate basic principles and techniques of fMRI, its applications, practical points to consider while performing and evaluating clinical fMRI and its limitations.

  3. Elucidating the Function of Penetratin and a Static Magnetic Field in Cellular Uptake of Magnetic Nanoparticles

    PubMed Central

    Chaudhary, Suman; Smith, Carol Anne; del Pino, Pablo; de la Fuente, Jesus M.; Mullin, Margaret; Hursthouse, Andrew; Stirling, David; Berry, Catherine C.

    2013-01-01

    Nanotechnology plays an increasingly important role in the biomedical arena. In particular, magnetic nanoparticles (mNPs) have become important tools in molecular diagnostics, in vivo imaging and improved treatment of disease, with the ultimate aim of producing a more theranostic approach. Due to their small sizes, the nanoparticles can cross most of the biological barriers such as the blood vessels and the blood brain barrier, thus providing ubiquitous access to most tissues. In all biomedical applications maximum nanoparticle uptake into cells is required. Two promising methods employed to this end include functionalization of mNPs with cell-penetrating peptides to promote efficient translocation of cargo into the cell and the use of external magnetic fields for enhanced delivery. This study aimed to compare the effect of both penetratin and a static magnetic field with regards to the cellular uptake of 200 nm magnetic NPs and determine the route of uptake by both methods. Results demonstrated that both techniques increased particle uptake, with penetratin proving more cell specific. Clathrin- medicated endocytosis appeared to be responsible for uptake as shown via PCR and western blot, with Pitstop 2 (known to selectively block clathrin formation) blocking particle uptake. Interestingly, it was further shown that a magnetic field was able to reverse or overcome the blocking, suggesting an alternative route of uptake. PMID:24275948

  4. Alignment of SWNTs by protein-ligand interaction of functionalized magnetic particles under low magnetic fields.

    PubMed

    Park, Tae Jung; Park, Jong Pil; Lee, Seok Jae; Jung, Dae-Hwan; Ko, Young Koan; Jung, Hee-Tae; Lee, Sang Yup

    2011-05-01

    Carbon nanotubes (CNTs) have attracted considerable attention for applications using their superior mechanical, thermal and electrical properties. A simple method to controllably align single-walled CNTs (SWNTs) by using magnetic particles embedded with superparamagnetic iron oxide as an accelerator under the magnetic field was developed. The functionalization of SWNTs using biotin, interacted with streptavidin-coupled magnetic particles (micro-to-nano in diameter), and layer-by-layer assembly were performed for the alignment of a particular direction onto the clean silicon and the gold substrate at very low magnetic forces (0.02-0.89 T) at room temperature. The successful alignment of the SWNTs with multi-layer film was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By changing the orientation and location of the substrates, crossed-networks of SWNTs-magnetic particle complex could easily be fabricated. We suggest that this approach, which consists of a combination of biological interaction among streptavidin-biotin and magnetite particles, should be useful for lateral orientation of individual SWNTs with controllable direction.

  5. Principal and independent component analysis of concomitant functional near infrared spectroscopy and magnetic resonance imaging data

    NASA Astrophysics Data System (ADS)

    Schelkanova, Irina; Toronov, Vladislav

    2011-07-01

    Although near infrared spectroscopy (NIRS) is now widely used both in emerging clinical techniques and in cognitive neuroscience, the development of the apparatuses and signal processing methods for these applications is still a hot research topic. The main unresolved problem in functional NIRS is the separation of functional signals from the contaminations by systemic and local physiological fluctuations. This problem was approached by using various signal processing methods, including blind signal separation techniques. In particular, principal component analysis (PCA) and independent component analysis (ICA) were applied to the data acquired at the same wavelength and at multiple sites on the human or animal heads during functional activation. These signal processing procedures resulted in a number of principal or independent components that could be attributed to functional activity but their physiological meaning remained unknown. On the other hand, the best physiological specificity is provided by broadband NIRS. Also, a comparison with functional magnetic resonance imaging (fMRI) allows determining the spatial origin of fNIRS signals. In this study we applied PCA and ICA to broadband NIRS data to distill the components correlating with the breath hold activation paradigm and compared them with the simultaneously acquired fMRI signals. Breath holding was used because it generates blood carbon dioxide (CO2) which increases the blood-oxygen-level-dependent (BOLD) signal as CO2 acts as a cerebral vasodilator. Vasodilation causes increased cerebral blood flow which washes deoxyhaemoglobin out of the cerebral capillary bed thus increasing both the cerebral blood volume and oxygenation. Although the original signals were quite diverse, we found very few different components which corresponded to fMRI signals at different locations in the brain and to different physiological chromophores.

  6. Structural and functional brain changes in early- and mid-stage primary open-angle glaucoma using voxel-based morphometry and functional magnetic resonance imaging.

    PubMed

    Jiang, Ming-Ming; Zhou, Qing; Liu, Xiao-Yong; Shi, Chang-Zheng; Chen, Jian; Huang, Xiang-He

    2017-03-01

    To investigate structural and functional brain changes in patients with primary open-angle glaucoma (POAG) by using voxel-based morphometry based on diffeomorphic anatomical registration through exponentiated Lie algebra (VBM-DARTEL) and blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI), respectively.Thirteen patients diagnosed with POAG and 13 age- and sex-matched healthy controls were enrolled in the study. For each participant, high-resolution structural brain imaging and blood flow imaging were acquired on a 3.0-Tesla magnetic resonance imaging (MRI) scanner. Structural and functional changes between the POAG and control groups were analyzed. An analysis was carried out to identify correlations between structural and functional changes acquired in the previous analysis and the retinal nerve fiber layer (RNFL).Patients in the POAG group showed a significant (P < 0.001) volume increase in the midbrain, left brainstem, frontal gyrus, cerebellar vermis, left inferior parietal lobule, caudate nucleus, thalamus, precuneus, and Brodmann areas 7, 18, and 46. Moreover, significant (P < 0.001) BOLD signal changes were observed in the right supramarginal gyrus, frontal gyrus, superior frontal gyrus, left inferior parietal lobule, left cuneus, and left midcingulate area; many of these regions had high correlations with the RNFL.Patients with POAG undergo widespread and complex changes in cortical brain structure and blood flow. (ClinicalTrials.gov number: NCT02570867).

  7. Structural and functional brain changes in early- and mid-stage primary open-angle glaucoma using voxel-based morphometry and functional magnetic resonance imaging

    PubMed Central

    Jiang, Ming-Ming; Zhou, Qing; Liu, Xiao-Yong; Shi, Chang-Zheng; Chen, Jian; Huang, Xiang-He

    2017-01-01

    Abstract To investigate structural and functional brain changes in patients with primary open-angle glaucoma (POAG) by using voxel-based morphometry based on diffeomorphic anatomical registration through exponentiated Lie algebra (VBM-DARTEL) and blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI), respectively. Thirteen patients diagnosed with POAG and 13 age- and sex-matched healthy controls were enrolled in the study. For each participant, high-resolution structural brain imaging and blood flow imaging were acquired on a 3.0-Tesla magnetic resonance imaging (MRI) scanner. Structural and functional changes between the POAG and control groups were analyzed. An analysis was carried out to identify correlations between structural and functional changes acquired in the previous analysis and the retinal nerve fiber layer (RNFL). Patients in the POAG group showed a significant (P < 0.001) volume increase in the midbrain, left brainstem, frontal gyrus, cerebellar vermis, left inferior parietal lobule, caudate nucleus, thalamus, precuneus, and Brodmann areas 7, 18, and 46. Moreover, significant (P < 0.001) BOLD signal changes were observed in the right supramarginal gyrus, frontal gyrus, superior frontal gyrus, left inferior parietal lobule, left cuneus, and left midcingulate area; many of these regions had high correlations with the RNFL. Patients with POAG undergo widespread and complex changes in cortical brain structure and blood flow. (ClinicalTrials.gov number: NCT02570867). PMID:28248867

  8. The physics of functional magnetic resonance imaging (fMRI)

    PubMed Central

    Buxton, Richard B

    2015-01-01

    Functional magnetic resonance imaging (fMRI) is a methodology for detecting dynamic patterns of activity in the working human brain. Although the initial discoveries that led to fMRI are only about 20 years old, this new field has revolutionized the study of brain function. The ability to detect changes in brain activity has a biophysical basis in the magnetic properties of deoxyhemoglobin, and a physiological basis in the way blood flow increases more than oxygen metabolism when local neural activity increases. These effects translate to a subtle increase in the local magnetic resonance signal, the blood oxygenation level dependent (BOLD) effect, when neural activity increases. With current techniques, this pattern of activation can be measured with resolution approaching 1 mm3 spatially and 1 s temporally. This review focuses on the physical basis of the BOLD effect, the imaging methods used to measure it, the possible origins of the physiological effects that produce a mismatch of blood flow and oxygen metabolism during neural activation, and the mathematical models that have been developed to understand the measured signals. An overarching theme is the growing field of quantitative fMRI, in which other MRI methods are combined with BOLD methods and analyzed within a theoretical modeling framework to derive quantitative estimates of oxygen metabolism and other physiological variables. That goal is the current challenge for fMRI: to move fMRI from a mapping tool to a quantitative probe of brain physiology. PMID:24006360

  9. How to Perform and Interpret Functional Magnetic Resonance Imaging Studies in Functional Gastrointestinal Disorders

    PubMed Central

    Lee, In-Seon; Preissl, Hubert; Enck, Paul

    2017-01-01

    Functional neuroimaging studies have revealed the importance of the role of cognitive and psychological factors and the dysregulation of the brain-gut axis in functional gastrointestinal disorder patients. Although only a small number of neuroimaging studies have been conducted in functional gastrointestinal disorder patients, and despite the fact that the neuroimaging technique requires a high level of knowledge, the technique still has a great deal of potential. The application of functional magnetic resonance imaging (fMRI) technique in functional gastrointestinal disorders should provide novel methods of diagnosing and treating patients. In this review, basic knowledge and technical/practical issues of fMRI will be introduced to clinicians. PMID:28256119

  10. Nuclear chiral and magnetic rotation in covariant density functional theory

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Zhao, Pengwei

    2016-05-01

    Excitations of chiral rotation observed in triaxial nuclei and magnetic and/or antimagnetic rotations (AMR) seen in near-spherical nuclei have attracted a lot of attention. Unlike conventional rotation in well-deformed or superdeformed nuclei, here the rotational axis is not necessary coinciding with any principal axis of the nuclear density distribution. Thus, tilted axis cranking (TAC) is mandatory to describe these excitations self-consistently in the framework of covariant density functional theory (CDFT). We will briefly introduce the formalism of TAC-CDFT and its application for magnetic and AMR phenomena. Configuration-fixed CDFT and its predictions for nuclear chiral configurations and for favorable triaxial deformation parameters are also presented, and the discoveries of the multiple chiral doublets in 133Ce and 103Rh are discussed.

  11. Magnetic field shift due to mechanical vibration in functional magnetic resonance imaging.

    PubMed

    Foerster, Bernd U; Tomasi, Dardo; Caparelli, Elisabeth C

    2005-11-01

    Mechanical vibrations of the gradient coil system during readout in echo-planar imaging (EPI) can increase the temperature of the gradient system and alter the magnetic field distribution during functional magnetic resonance imaging (fMRI). This effect is enhanced by resonant modes of vibrations and results in apparent motion along the phase encoding direction in fMRI studies. The magnetic field drift was quantified during EPI by monitoring the resonance frequency interleaved with the EPI acquisition, and a novel method is proposed to correct the apparent motion. The knowledge on the frequency drift over time was used to correct the phase of the k-space EPI dataset. Since the resonance frequency changes very slowly over time, two measurements of the resonance frequency, immediately before and after the EPI acquisition, are sufficient to remove the field drift effects from fMRI time series. The frequency drift correction method was tested "in vivo" and compared to the standard image realignment method. The proposed method efficiently corrects spurious motion due to magnetic field drifts during fMRI.

  12. Fast Instability Caused by Electron Cloud in Combined Function Magnets

    SciTech Connect

    Antipov, S. A.; Adamson, P.; Burov, A.; Nagaitsev, S.; Yang, M. J.

    2016-12-12

    One of the factors which may limit the intensity in the Fermilab Recycler is a fast transverse instability. It develops within a hundred turns and, in certain conditions, may lead to a beam loss. The high rate of the instability suggest that its cause is electron cloud. We studied the phenomena by observing the dynamics of stable and unstable beam, simulating numerically the build-up of the electron cloud, and developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function di-poles. We found that beam motion can be stabilized by a clearing bunch, which confirms the electron cloud nature of the instability. The clearing suggest electron cloud trapping in Recycler combined function mag-nets. Numerical simulations show that up to 1% of the particles can be trapped by the magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multi-turn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The estimated resulting instability growth rate of about 30 revolutions and the mode fre-quency of 0.4 MHz are consistent with experimental observations and agree with the simulation in the PEI code. The created instability model allows investigating the beam stability for the future intensity upgrades.

  13. Two-way principal component analysis for matrix-variate data, with an application to functional magnetic resonance imaging data.

    PubMed

    Huang, Lei; Reiss, Philip T; Xiao, Luo; Zipunnikov, Vadim; Lindquist, Martin A; Crainiceanu, Ciprian M

    2016-08-29

    SummaryMany modern neuroimaging studies acquire large spatial images of the brain observed sequentially over time. Such data are often stored in the forms of matrices. To model these matrix-variate data we introduce a class of separable processes using explicit latent process modeling. To account for the size and two-way structure of the data, we extend principal component analysis to achieve dimensionality reduction at the individual level. We introduce necessary identifiability conditions for each model and develop scalable estimation procedures. The method is motivated by and applied to a functional magnetic resonance imaging study designed to analyze the relationship between pain and brain activity.

  14. The economics of functional magnetic resonance imaging: clinical and research.

    PubMed

    Yousem, David M

    2014-11-01

    It is difficult to justify maintaining a clinical functional magnetic resonance imaging (fMRI) program based solely on revenue generation. The use of fMRI is, therefore, based mostly in patient care considerations, leading to better outcomes. The high costs of the top-of-the-line equipment, hardware, and software needed for state-of-the-art fMRI and the time commitment by multiple professionals are not adequately reimbursed at a representative rate by current payor schemes for the Current Procedure Terminology codes assigned.

  15. Peptide-functionalized iron oxide magnetic nanoparticle for gold mining

    NASA Astrophysics Data System (ADS)

    Shen, Wei-Zheng; Cetinel, Sibel; Sharma, Kumakshi; Borujeny, Elham Rafie; Montemagno, Carlo

    2017-02-01

    Here, we present our work on preparing a novel nanomaterial composed of inorganic binding peptides and magnetic nanoparticles for inorganic mining. Two previously selected and well-characterized gold-binding peptides from cell surface display, AuBP1 and AuBP2, were exploited. This nanomaterial (AuBP-MNP) was designed to fulfill the following two significant functions: the surface conjugated gold-binding peptide will recognize and selectively bind to gold, while the magnetic nano-sized core will respond and migrate according to the applied external magnetic field. This will allow the smart nanomaterial to mine an individual material (gold) from a pool of mixture, without excessive solvent extraction, filtration, and concentration steps. The working efficiency of AuBP-MNP was determined by showing a dramatic reduction of gold nanoparticle colloid concentration, monitored by spectroscopy. The binding kinetics of AuBP-MNP onto the gold surface was determined using surface plasmon resonance (SPR) spectroscopy, which exhibits around 100 times higher binding kinetics than peptides alone. The binding capacity of AuBP-MNP was demonstrated by a bench-top mining test with gold microparticles.

  16. A dual RF resonator system for high-field functional magnetic resonance imaging of small animals.

    PubMed

    Ludwig, R; Bodgdanov, G; King, J; Allard, A; Ferris, C F

    2004-01-30

    A new apparatus has been developed that integrates an animal restrainer arrangement for small animals with an actively tunable/detunable dual radio-frequency (RF) coil system for in vivo anatomical and functional magnetic resonance imaging of small animals at 4.7 T. The radio-frequency coil features an eight-element microstrip line configuration that, in conjunction with a segmented outer copper shield, forms a transversal electromagnetic (TEM) resonator structure. Matching and active tuning/detuning is achieved through fixed/variable capacitors and a PIN diode for each resonator element. These components along with radio-frequency chokes (RFCs) and blocking capacitors are placed on two printed circuit boards (PCBs) whose copper coated ground planes form the front and back of the volume coil and are therefore an integral part of the resonator structure. The magnetic resonance signal response is received with a dome-shaped single-loop surface coil that can be height-adjustable with respect to the animal's head. The conscious animal is immobilized through a mechanical arrangement that consists of a Plexiglas body tube and a head restrainer. This restrainer has a cylindrical holder with a mouthpiece and position screws to receive and restrain the head of the animal. The apparatus is intended to perform anatomical and functional magnetic resonance imaging in conscious animals such as mice, rats, hamsters, and marmosets. Cranial images acquired from fully conscious rats in a 4.7 T Bruker 40 cm bore animal scanner underscore the feasibility of this approach and bode well to extend this system to the imaging of other animals.

  17. Localizing the site of magnetic brain stimulation by functional MRI.

    PubMed

    Terao, Y; Ugawa, Y; Sakai, K; Miyauchi, S; Fukuda, H; Sasaki, Y; Takino, R; Hanajima, R; Furubayashi, T; Pütz, B; Kanazawa, I

    1998-07-01

    In order to locate the site of action of transcranial magnetic stimulation (TMS) within the human motor cortices, we investigated how the optimal positions for evoking motor responses over the scalp corresponded to the hand and leg primary-motor areas. TMS was delivered with a figure-8 shaped coil over each point of a grid system constructed on the skull surface, each separated by 1 cm, to find the optimal site for obtaining motor-evoked potentials (MEPs) in the contralateral first dorsal interosseous (FDI) and tibialis anterior (TA) muscles. Magnetic resonance imaging scans of the brain were taken for each subject with markers placed over these sites, the positions of which were projected onto the cortical region just beneath. On the other hand, cortical areas where blood flow increased during finger tapping or leg movements were identified on functional magnetic resonance images (fMRI), which should include the hand and leg primary-motor areas. The optimal location for eliciting MEPs in FDI, regardless of their latency, lay just above the bank of the precentral gyrus, which coincided with the activated region during finger tapping in fMRI studies. The direction of induced current preferentially eliciting MEPs with the shortest latency in each subject was nearly perpendicular to the course of the precentral gyrus at this position. The optimal site for evoking motor responses in TA was also located just above the activated area during leg movements identified within the anterior portion of the paracentral lobule. The results suggest that, for magnetic stimulation, activation occurs in the primary hand and leg motor area (Brodmann area 4), which is closest in distance to the optimal scalp position for evoking motor responses.

  18. Functional magnetic resonance imaging as a management tool for cerebral arteriovenous malformations.

    PubMed

    Latchaw, R E; Hu, X; Ugurbil, K; Hall, W A; Madison, M T; Heros, R C

    1995-10-01

    The location of eloquent cortex, such as the motor strip, the visual cortex, or Broca's area, may be difficult to predict even with multiprojectional magnetic resonance imaging (MRI). Distortion and displacement of this cortex may occur with a congenital lesion, such as an arteriovenous malformation, or by an acquired disease, such as a neoplasm. A desire to avoid damaging these eloquent areas by conventional surgery, radiosurgery, or endovascular surgery makes their accurate identification an important part of the pretherapeutic planning process. Blood oxygen level dependent functional MRI is a technique that uses the local increase of oxyhemoglobin concentration in the patient that occurs as a result of the increase in flow rate and blood volume in eloquent cortex undergoing stimulation from, for example, flashing lights, hand movements, or speech. We have used the blood oxygen level dependent technique to localize eloquent cortex relative to arteriovenous malformations and tumors. Using a 4.0-T magnetic resonance (MR) system, there is a sufficiently high degree of spatial resolution of the MR signal intensity changes during stimulation to allow the identification of eloquent cortex. Alternative, non-MR, invasive techniques for functional localization include electrocorticography and stimulation from subdural grids and strips. Noninvasive, non-MR technologies, such as positron emission tomography and magnetoencephalography, can also provide functional localization of eloquent cortex. However, the perfection of functional MRI at the 1.5-T field strength and the large number of such MR systems in operation mean that a highly accurate cerebral cortical localization technique can be available to most neuroscientists without the need to purchase alternative expensive technology.

  19. Room-temperature Magnetic Ordering in Functionalized Graphene

    PubMed Central

    Hong, Jeongmin; Bekyarova, Elena; Liang, Ping; de Heer, Walt A.; Haddon, Robert C.; Khizroev, Sakhrat

    2012-01-01

    Despite theoretical predictions, the question of room-temperature magnetic order in graphene must be conclusively resolved before graphene can fully achieve its potential as a spintronic medium. Through scanning tunneling microscopy (STM) and point I-V measurements, the current study reveals that unlike pristine samples, graphene nanostructures, when functionalized with aryl radicals, can sustain magnetic order. STM images show 1-D and 2-D periodic super-lattices originating from the functionalization of a single sub-lattice of the bipartite graphene structure. Field-dependent super-lattices in 3-nm wide “zigzag” nanoribbons indicate local moments with parallel and anti-parallel ordering along and across the edges, respectively. Anti-parallel ordering is observed in 2-D segments with sizes of over 20 nm. The field dependence of STM images and point I-V curves indicates a spin polarized local density of states (LDOS), an out-of-plane anisotropy field of less than 10 Oe, and an exchange coupling field of 100 Oe at room temperature. PMID:22953045

  20. Desmosomes in acquired disease

    PubMed Central

    Stahley, Sara N.; Kowalczyk, Andrew P.

    2015-01-01

    Desmosomes are cell-cell junctions that mediate adhesion and couple the intermediate filament cytoskeleton to sites of cell-cell contact. This architectural arrangement functions to integrate adhesion and cytoskeletal elements of adjacent cells. The importance of this robust adhesion system is evident in numerous human diseases, both inherited and acquired, that occur when desmosome function is compromised. This review focuses on autoimmune and infectious diseases that impair desmosome function. In addition, we discuss emerging evidence that desmosomal genes are often misregulated in cancer. The emphasis of our discussion is placed on how human diseases inform our understanding of basic desmosome biology, and in turn, how fundamental advances in the cell biology of desmosomes may lead to new treatments for acquired diseases of the desmosome. PMID:25795143

  1. Probing Corticospinal Recruitment Patterns and Functional Synergies with Transcranial Magnetic Stimulation

    PubMed Central

    Mathew, James; Kübler, Angelika; Bauer, Robert; Gharabaghi, Alireza

    2016-01-01

    Background: On the one hand, stimulating the motor cortex at different spots may activate the same muscle and result in a muscle-specific cortical map. Maps of different muscles, which are functionally coupled, may present with a large overlap but may also show a relevant variability. On the other hand, stimulation of the motor cortex at one spot with different stimulation intensities results in a characteristic input–output (IO) curve for one specific muscle but may simultaneously also activate different, functionally coupled muscles. A comparison of the cortical map overlap of synergistic muscles and their IO curves has not yet been carried out. Objective: The aim of this study was to probe functional synergies of forearm muscles with transcranial magnetic stimulation by harnessing the convergence and divergence of the corticospinal output. Methods: We acquired bihemispheric cortical maps and IO curves of the extensor carpi ulnaris, extensor carpi radialis, and extensor digitorum communis muscles by subjecting 11 healthy subjects to both monophasic and biphasic pulse waveforms. Results: The degree of synergy between pairs of forearm muscles was captured by the overlap of the cortical motor maps and the respective IO curves which were influenced by the pulse waveform. Monophasic and biphasic stimulation were particularly suitable for disentangling synergistic muscles in the right and left hemisphere, respectively. Conclusion: Combining IO curves and different pulse waveforms may provide complementary information on neural circuit dynamics and corticospinal recruitment patterns of synergistic muscles and their neuroplastic modulation. PMID:27458344

  2. A General Method for Calculating the External Magnetic Field from a Cylindrical Magnetic Source using Toroidal Functions

    SciTech Connect

    J Selvaggi; S Salon; O Kwon CVK Chari

    2006-02-14

    An alternative method is developed to compute the magnetic field from a circular cylindrical magnetic source. Specifically, a Fourier series expansion whose coefficients are toroidal functions is introduced which yields an alternative to the more familiar spherical harmonic solution or the Elliptic integral solution. This alternate formulation coupled with a method called charge simulation allows one to compute the external magnetic field from an arbitrary magnetic source in terms of a toroidal expansion. This expansion is valid on any finite hypothetical external observation cylinder. In other words, the magnetic scalar potential or the magnetic field intensity is computed on a exterior cylinder which encloses the magnetic source. This method can be used to accurately compute the far field where a finite element formulation is known to be inaccurate.

  3. A resting state functional magnetic resonance imaging study of concussion in collegiate athletes.

    PubMed

    Czerniak, Suzanne M; Sikoglu, Elif M; Liso Navarro, Ana A; McCafferty, Joseph; Eisenstock, Jordan; Stevenson, J Herbert; King, Jean A; Moore, Constance M

    2015-06-01

    Sports-related concussions are currently diagnosed through multi-domain assessment by a medical professional and may utilize neurocognitive testing as an aid. However, these tests have only been able to detect differences in the days to week post-concussion. Here, we investigate a measure of brain function, namely resting state functional connectivity, which may detect residual brain differences in the weeks to months after concussion. Twenty-one student athletes (9 concussed within 6 months of enrollment; 12 non-concussed; between ages 18 and 22 years) were recruited for this study. All participants completed the Wisconsin Card Sorting Task and the Color-Word Interference Test. Neuroimaging data, specifically resting state functional Magnetic Resonance Imaging data, were acquired to examine resting state functional connectivity. Two sample t-tests were used to compare the neurocognitive scores and resting state functional connectivity patterns among concussed and non-concussed participants. Correlations between neurocognitive scores and resting state functional connectivity measures were also determined across all subjects. There were no significant differences in neurocognitive performance between concussed and non-concussed groups. Concussed subjects had significantly increased connections between areas of the brain that underlie executive function. Across all subjects, better neurocognitive performance corresponded to stronger brain connectivity. Even at rest, brains of concussed athletes may have to 'work harder' than their healthy peers to achieve similar neurocognitive results. Resting state brain connectivity may be able to detect prolonged brain differences in concussed athletes in a more quantitative manner than neurocognitive test scores.

  4. A Resting State Functional Magnetic Resonance Imaging Study of Concussion in Collegiate Athletes

    PubMed Central

    Czerniak, Suzanne M; Sikoglu, Elif M; Navarro, Ana A Liso; McCafferty, Joseph; Eisenstock, Jordan; Stevenson, J Herbert; King, Jean A; Moore, Constance M

    2015-01-01

    Sports-related concussions are currently diagnosed through multi-domain assessment by a medical professional and may utilize neurocognitive testing as an aide. However, these tests have only been able to detect differences in the days to week post-concussion. Here, we investigate a measure of brain function, namely resting state functional connectivity, which may detect residual brain differences in the weeks to months after concussion. Twenty-one student athletes (9 concussed within 6 months of enrollment; 12 non-concussed; between ages 18 to 22 years) were recruited for this study. All participants completed the Wisconsin Card Sort Task and the Color-Word Interference Test. Neuroimaging data, specifically resting state functional Magnetic Resonance Imaging data, were acquired to examine resting state functional connectivity. Two sample t-tests were used to compare the neurocognitive scores and resting state functional connectivity patterns among concussed and non-concussed participants. Correlations between neurocognitive scores and resting state functional connectivity measures were also determined across all subjects. There were no significant differences in neurocognitive performance between concussed and non-concussed groups. Concussed subjects had significantly increased connections between areas of the brain that underlie executive function. Across all subjects, better neurocognitive performance corresponded to stronger brain connectivity. Even at rest, brains of concussed athletes may have to ‘work harder’ than their healthy peers to achieve similar neurocognitive results. Resting state brain connectivity may be able to detect prolonged brain differences in concussed athletes in a more quantitative manner than neurocognitive test scores. PMID:25112544

  5. Continuous theta burst transcranial magnetic stimulation affects brain functional connectivity.

    PubMed

    Dan Cao; Yingjie Li; Ling Wei; Yingying Tang

    2016-08-01

    Prefrontal cortex (PFC) plays an important role in the emotional processing as well as in the functional brain network. Hyperactivity in the right dorsolateral prefrontal cortex (DLPFC) would be found in anxious participants. However, it is still unclear what the role of PFC played in a resting functional network. Continuous theta burst transcranial magnetic stimulation (cTBS) is an effective tool to create virtual lesions on brain regions. In this paper, we applied cTBS over right prefrontal area, and investigated the effects of cTBS on the brain activity for functional connectivity by the method of graph theory. We recorded 64-channels EEG on thirteen healthy participants in the resting condition and emotional tasks before and after 40 s of cTBS. This work focused on the effect of cTBS on cortical activities in the resting condition by calculating the coherence between EEG channels and building functional networks before and after cTBS in the delta, theta, alpha and beta bands. Results revealed that 1) The functional connectivity after cTBS was significantly increased compared with that before cTBS in delta, theta, alpha and beta bands in the resting condition; 2) The efficiency-cost reached the maximum before and after cTBS both with the cost about 0.3 in the bands above, which meant that the information transmission of functional brain network with this cost was highly efficient; 3) the clustering coefficient and path length after cTBS was significantly increased in delta, theta and beta bands. In conclusion, cTBS over PFC indeed enhanced the functional connectivity in the resting condition. In addition, the information transmission in the resting brain network was highly efficient with the cost about 0.3.

  6. Modulating functional and dysfunctional mentalizing by transcranial magnetic stimulation

    PubMed Central

    Schuwerk, Tobias; Langguth, Berthold; Sommer, Monika

    2014-01-01

    Mentalizing, the ability to attribute mental states to others and oneself, is a cognitive function with high relevance for social interactions. Recent neuroscientific research has increasingly contributed to attempts to decompose this complex social cognitive function into constituting neurocognitive building blocks. Additionally, clinical research that focuses on social cognition to find links between impaired social functioning and neurophysiological deviations has accumulated evidence that mentalizing is affected in most psychiatric disorders. Recently, both lines of research have started to employ transcranial magnetic stimulation: the first to modulate mentalizing in order to specify its neurocognitive components, the latter to treat impaired mentalizing in clinical conditions. This review integrates findings of these two different approaches to draw a more detailed picture of the neurocognitive basis of mentalizing and its deviations in psychiatric disorders. Moreover, we evaluate the effectiveness of hitherto employed stimulation techniques and protocols, paradigms and outcome measures. Based on this overview we highlight new directions for future research on the neurocognitive basis of functional and dysfunctional social cognition. PMID:25477838

  7. Longitudinal Functional Magnetic Resonance Imaging in Animal Models

    PubMed Central

    Silva, Afonso C.; Liu, Junjie V.; Hirano, Yoshiyuki; Leoni, Renata F.; Merkle, Hellmut; Mackel, Julie B.; Zhang, Xian Feng; Nascimento, George C.; Stefanovic, Bojana

    2016-01-01

    Functional magnetic resonance imaging (fMRI) has had an essential role in furthering our understanding of brain physiology and function. fMRI techniques are nowadays widely applied in neuroscience research, as well as in translational and clinical studies. The use of animal models in fMRI studies has been fundamental in helping elucidate the mechanisms of cerebral blood flow regulation, and in the exploration of basic neuroscience questions, such as the mechanisms of perception, behavior, and cognition. Because animals are inherently noncompliant, most fMRI performed to date have required the use of anesthesia, which interferes with brain function and compromises interpretability and applicability of results to our understanding of human brain function. An alternative approach that eliminates the need for anesthesia involves training the animal to tolerate physical restraint during the data acquisition. In the present work we review these two different approaches to obtaining fMRI data from animal models, with a specific focus on the acquisition of longitudinal data from the same subjects. PMID:21279608

  8. Functional magnetic resonance imaging of mild traumatic brain injury.

    PubMed

    Mayer, Andrew R; Bellgowan, Patrick S F; Hanlon, Faith M

    2015-02-01

    Functional magnetic resonance imaging (fMRI) offers great promise for elucidating the neuropathology associated with a single or repetitive mild traumatic brain injury (mTBI). The current review discusses the physiological underpinnings of the blood-oxygen level dependent response and how trauma affects the signal. Methodological challenges associated with fMRI data analyses are considered next, followed by a review of current mTBI findings. The majority of evoked studies have examined working memory and attentional functioning, with results suggesting a complex relationship between cognitive load/attentional demand and neuronal activation. Researchers have more recently investigated how brain trauma affects functional connectivity, and the benefits/drawbacks of evoked and functional connectivity studies are also discussed. The review concludes by discussing the major clinical challenges associated with fMRI studies of brain-injured patients, including patient heterogeneity and variations in scan-time post-injury. We conclude that the fMRI signal represents a complex filter through which researchers can measure the physiological correlates of concussive symptoms, an important goal for the burgeoning field of mTBI research.

  9. Hyperpolarized Xenon-129 Magnetic Resonance Imaging of Functional Lung Microstructure

    NASA Astrophysics Data System (ADS)

    Dregely, Isabel

    Hyperpolarized 129Xe (HXe) is a non-invasive contrast agent for lung magnetic resonance imaging (MRI), which upon inhalation follows the functional pathway of oxygen in the lung by dissolving into lung tissue structures and entering the blood stream. HXe MRI therefore provides unique opportunities for functional lung imaging of gas exchange which occurs from alveolar air spaces across the air-blood boundary into parenchymal tissue. However challenges in acquisition speed and signal-to-noise ratio have limited the development of a HXe imaging biomarker to diagnose lung disease. This thesis addresses these challenges by introducing parallel imaging to HXe MRI. Parallel imaging requires dedicated hardware. This work describes design, implementation, and characterization of a 32-channel phased-array chest receive coil with an integrated asymmetric birdcage transmit coil tuned to the HXe resonance on a 3 Tesla MRI system. Using the newly developed human chest coil, a functional HXe imaging method, multiple exchange time xenon magnetization transfer contrast (MXTC) is implemented. MXTC dynamically encodes HXe gas exchange into the image contrast. This permits two parameters to be derived regionally which are related to gas-exchange functionality by characterizing tissue-to-alveolar-volume ratio and alveolar wall thickness in the lung parenchyma. Initial results in healthy subjects demonstrate the sensitivity of MXTC by quantifying the subtle changes in lung microstructure in response to orientation and lung inflation. Our results in subjects with lung disease show that the MXTC-derived functional tissue density parameter exhibits excellent agreement with established imaging techniques. The newly developed dynamic parameter, which characterizes the alveolar wall, was elevated in subjects with lung disease, most likely indicating parenchymal inflammation. In light of these observations we believe that MXTC has potential as a biomarker for the regional quantification of 1

  10. Functional magnetic resonance imaging and the brain: A brief review

    PubMed Central

    Chow, Maggie S M; Wu, Sharon L; Webb, Sarah E; Gluskin, Katie; Yew, D T

    2017-01-01

    Functional magnetic resonance imaging (fMRI) is employed in many behavior analysis studies, with blood oxygen level dependent- (BOLD-) contrast imaging being the main method used to generate images. The use of BOLD-contrast imaging in fMRI has been refined over the years, for example, the inclusion of a spin echo pulse and increased magnetic strength were shown to produce better recorded images. Taking careful precautions to control variables during measurement, comparisons between different specimen groups can be illustrated by fMRI imaging using both quantitative and qualitative methods. Differences have been observed in comparisons of active and resting, developing and aging, and defective and damaged brains in various studies. However, cognitive studies using fMRI still face a number of challenges in interpretation that can only be overcome by imaging large numbers of samples. Furthermore, fMRI studies of brain cancer, lesions and other brain pathologies of both humans and animals are still to be explored. PMID:28144401

  11. Desmosomes in acquired disease.

    PubMed

    Stahley, Sara N; Kowalczyk, Andrew P

    2015-06-01

    Desmosomes are cell-cell junctions that mediate adhesion and couple the intermediate filament cytoskeleton to sites of cell-cell contact. This architectural arrangement integrates adhesion and cytoskeletal elements of adjacent cells. The importance of this robust adhesion system is evident in numerous human diseases, both inherited and acquired, which occur when desmosome function is compromised. This review focuses on autoimmune and infectious diseases that impair desmosome function. In addition, we discuss emerging evidence that desmosomal genes are often misregulated in cancer. The emphasis of our discussion is placed on the way in which human diseases can inform our understanding of basic desmosome biology and in turn, the means by which fundamental advances in the cell biology of desmosomes might lead to new treatments for acquired diseases of the desmosome.

  12. Mapping social target detection with functional magnetic resonance imaging.

    PubMed

    Dichter, Gabriel S; Felder, Jennifer N; Bodfish, James W; Sikich, Linmarie; Belger, Aysenil

    2009-03-01

    The neural correlates of cognitive control and social processing functions, as well as the characteristic patterns of anomalous brain activation patterns in psychiatric conditions associated with impairment in these functions, have been well characterized. However, these domains have primarily been examined in isolation. The present study used event-related functional magnetic resonance imaging to map brain areas recruited during a target-detection task designed to evaluate responses to both non-social (i.e. shape) and social (i.e. face) target stimuli. Both shape and face targets activated a similar brain network, including the postcentral gyrus, the anterior and posterior cingulate gyri and the right midfrontal gyrus, whereas face targets additionally activated the thalamus, fusiform and temporooccipital cortex, lingual gyrus and paracingulate gyrus. Comparison of activations to social and non-social target events revealed that a small portion of the dorsal anterior cingulate gyrus (Brodmann's area 32) and the supracalcarine cortex were preferentially activated to face targets. These findings indicate that non-social and social stimuli embedded within a cognitive control task activate overlapping and distinct brain regions. Clinical cognitive neuroscience research of disorders characterized by cognitive dysfunction and impaired social processing would benefit from the use of tasks that evaluate the combined effects of deficits in these two domains.

  13. Functional magnetic resonance imaging: imaging techniques and contrast mechanisms.

    PubMed Central

    Howseman, A M; Bowtell, R W

    1999-01-01

    Functional magnetic resonance imaging (fMRI) is a widely used technique for generating images or maps of human brain activity. The applications of the technique are widespread in cognitive neuroscience and it is hoped they will eventually extend into clinical practice. The activation signal measured with fMRI is predicated on indirectly measuring changes in the concentration of deoxyhaemoglobin which arise from an increase in blood oxygenation in the vicinity of neuronal firing. The exact mechanisms of this blood oxygenation level dependent (BOLD) contrast are highly complex. The signal measured is dependent on both the underlying physiological events and the imaging physics. BOLD contrast, although sensitive, is not a quantifiable measure of neuronal activity. A number of different imaging techniques and parameters can be used for fMRI, the choice of which depends on the particular requirements of each functional imaging experiment. The high-speed MRI technique, echo-planar imaging provides the basis for most fMRI experiments. The problems inherent to this method and the ways in which these may be overcome are particularly important in the move towards performing functional studies on higher field MRI systems. Future developments in techniques and hardware are also likely to enhance the measurement of brain activity using MRI. PMID:10466145

  14. Functional magnetic resonance imaging of autism spectrum disorders.

    PubMed

    Dichter, Gabriel S

    2012-09-01

    This review presents an overview of functional magnetic resonance imaging findings in autism spectrum disorders (ASDS), although there is considerable heterogeneity with respect to results across studies, common themes have emerged, including: (i) hypoactivation in nodes of the "social brain" during social processing tasks, including regions within the prefrontal cortex, the posterior superior temporal sulcus, the amygdala, and the fusiform gyrus; (ii) aberrant frontostriatal activation during cognitive control tasks relevant to restricted and repetitive behaviors and interests, including regions within the dorsal prefrontal cortex and the basal ganglia; (iii) differential lateralization and activation of language processing and production regions during communication tasks; (iv) anomalous mesolimbic responses to social and nonsocial rewards; (v) task-based long-range functional hypoconnectivity and short-range hyper-connectivity; and (vi) decreased anterior-posterior functional connectivity during resting states. These findings provide mechanistic accounts of ASD pathophysiology and suggest directions for future research aimed at elucidating etiologic models and developing rationally derived and targeted treatments.

  15. Functional magnetic resonance imaging of autism spectrum disorders

    PubMed Central

    Dichter, Gabriel S.

    2012-01-01

    This review presents an overview of functional magnetic resonance imaging findings in autism spectrum disorders (ASDs), Although there is considerable heterogeneity with respect to results across studies, common themes have emerged, including: (i) hypoactivation in nodes of the “social brain” during social processing tasks, including regions within the prefrontal cortex, the posterior superior temporal sulcus, the amygdala, and the fusiform gyrus; (ii) aberrant frontostriatal activation during cognitive control tasks relevant to restricted and repetitive behaviors and interests, including regions within the dorsal prefrontal cortex and the basal ganglia; (iii) differential lateralization and activation of language processing and production regions during communication tasks; (iv) anomalous mesolimbic responses to social and nonsocial rewards; (v) task-based long-range functional hypoconnectivity and short-range hyper-connectivity; and (vi) decreased anterior-posterior functional connectivity during resting states. These findings provide mechanistic accounts of ASD pathophysiology and suggest directions for future research aimed at elucidating etiologic models and developing rationally derived and targeted treatments. PMID:23226956

  16. Functional assessment of transplanted kidneys with magnetic resonance imaging.

    PubMed

    Wang, Yu-Ting; Li, Ying-Chun; Yin, Long-Lin; Pu, Hong; Chen, Jia-Yuan

    2015-10-28

    Kidney transplantation has emerged as the treatment of choice for many patients with end-stage renal disease, which is a significant cause of morbidity and mortality. Given the shortage of clinically available donor kidneys and the significant incidence of allograft dysfunction, a noninvasive and accurate assessment of the allograft renal function is critical for postoperative management. Prompt diagnosis of graft dysfunction facilitates clinical intervention of kidneys with salvageable function. New advances in magnetic resonance imaging (MRI) technology have enabled the calculation of various renal parameters that were previously not feasible to measure noninvasively. Diffusion-weighted imaging provides information on renal diffusion and perfusion simultaneously, with quantification by the apparent diffusion coefficient, the decrease of which reflects renal function impairment. Diffusion-tensor imaging accounts for the directionality of molecular motion and measures fractional anisotropy of the kidneys. Blood oxygen level-dependent MR evaluates intrarenal oxygen bioavailability, generating the parameter of R2* (reflecting the concentration of deoxyhemoglobin). A decrease in R2* could happen during acute rejection. MR nephro-urography/renography demonstrates structural data depicting urinary tract obstructions and functional data regarding the glomerular filtration and blood flow. MR angiography details the transplant vasculature and is particularly suitable for detecting vascular complications, with good correlation with digital subtraction angiography. Other functional MRI technologies, such as arterial spin labeling and MR spectroscopy, are showing additional promise. This review highlights MRI as a comprehensive modality to diagnose a variety of etiologies of graft dysfunction, including prerenal (e.g., renal vasculature), renal (intrinsic causes) and postrenal (e.g., obstruction of the collecting system) etiologies.

  17. Surface functionalized magnetic nanoparticles for cancer therapy applications

    NASA Astrophysics Data System (ADS)

    Wydra, Robert John

    Despite recent advances, cancer remains the second leading cause of deaths in the United States. Magnetic nanoparticles have found various applications in cancer research as drug delivery platforms, enhanced contrast agents for improved diagnostic imaging, and the delivery of thermal energy as standalone therapy. Iron oxide nanoparticles absorb the energy from an alternating magnetic field and convert it into heat through Brownian and Neel relaxations. To better utilize magnetic nanoparticles for cancer therapy, surface functionalization is essential for such factors as decreasing cytotoxicity of healthy tissue, extending circulation time, specific targeting of cancer cells, and manage the controlled delivery of therapeutics. In the first study, iron oxide nanoparticles were coated with a poly(ethylene glycol) (PEG) based polymer shell. The PEG coating was selected to prevent protein adsorption and thus improve circulation time and minimize host response to the nanoparticles. Thermal therapy application feasibility was demonstrated in vitro with a thermoablation study on lung carcinoma cells. Building on the thermal therapy demonstration with iron oxide nanoparticles, the second area of work focused on intracellular delivery. Nanoparticles can be appropriately tailored to enter the cell and deliver energy on the nanoscale eliminating individual cancer cells. The underlying mechanism of action is still under study, and we were interested in determining the role of reactive oxygen species (ROS) catalytically generated from the surface of iron oxide nanoparticles in this measured cytotoxicity. When exposed to an AMF, the nanoscale heating effects are capable of enhancing the Fenton-like generation of ROS determined through a methylene blue degradation assay. To deliver this enhanced ROS effect to cells, monosaccharide coated nanoparticles were developed and successfully internalized by colon cancer cell lines. Upon AMF exposure, there was a measured increase in

  18. Functional recovery in hemiplegic cerebral palsy: ipsilateral electromyographic responses to focal transcranial magnetic stimulation.

    PubMed

    Nezu, A; Kimura, S; Takeshita, S; Tanaka, M

    1999-04-01

    The patterns of functional recovery after unilateral cerebral damage occurring in the prenatal to infantile periods were studied in nine patients with hemiplegic cerebral palsy. Motor evoked potentials (MEPs) recorded from the small hand muscles were investigated using focal transcranial magnetic stimulation (TMS). The MEPs findings could be separated into three subtypes based on the features of ipsilateral MEPs elicited by TMS over the unaffected motor cortex. Bilateral MEPs of similar latency were obtained in three patients. These patients each having a congenital lesion invariably exhibited mirror movements and severe hemiparesis. Meanwhile, ipsilateral MEPs with markedly prolonged latency were demonstrated in two other patients, who exhibited synergistic associated movements and severe hemiparesis caused by an acquired lesion. In the remaining four patients, who showed mild hemiparesis without such abnormal interlimb coordinations, there were no ipsilateral MEPs. Thus, we suggest that TMS is useful for confirming the electrophysiological findings relevant to functional recovery in hemiplegic cerebral palsy underlying such abnormal interlimb coordinations. Specifically, bilateral MEPs of similar latency were considered consistent with compensatory mirror movements originating from bilateral motor representation in the unaffected motor cortex.

  19. Event-related single-shot volumetric functional magnetic resonance inverse imaging of visual processing.

    PubMed

    Lin, Fa-Hsuan; Witzel, Thomas; Mandeville, Joseph B; Polimeni, Jonathan R; Zeffiro, Thomas A; Greve, Douglas N; Wiggins, Graham; Wald, Lawrence L; Belliveau, John W

    2008-08-01

    Developments in multi-channel radio-frequency (RF) coil array technology have enabled functional magnetic resonance imaging (fMRI) with higher degrees of spatial and temporal resolution. While modest improvement in temporal acceleration has been achieved by increasing the number of RF coils, the maximum attainable acceleration in parallel MRI acquisition is intrinsically limited only by the amount of independent spatial information in the combined array channels. Since the geometric configuration of a large-n MRI head coil array is similar to that used in EEG electrode or MEG SQUID sensor arrays, the source localization algorithms used in MEG or EEG source imaging can be extended to also process MRI coil array data, resulting in greatly improved temporal resolution by minimizing k-space traversal during signal acquisition. Using a novel approach, we acquire multi-channel MRI head coil array data and then apply inverse reconstruction methods to obtain volumetric fMRI estimates of blood oxygenation level dependent (BOLD) contrast at unprecedented whole-brain acquisition rates of 100 ms. We call this combination of techniques magnetic resonance Inverse Imaging (InI), a method that provides estimates of dynamic spatially-resolved signal change that can be used to construct statistical maps of task-related brain activity. We demonstrate the sensitivity and inter-subject reliability of volumetric InI using an event-related design to probe the hemodynamic signal modulations in primary visual cortex. Robust results from both single subject and group analyses demonstrate the sensitivity and feasibility of using volumetric InI in high temporal resolution investigations of human brain function.

  20. Event-related Single-shot Volumetric Functional Magnetic Resonance Inverse Imaging of Visual Processing

    PubMed Central

    Lin, Fa-Hsuan; Witzel, Thomas; Mandeville, Joseph B.; Polimeni, Jonathan R.; Zeffiro, Thomas A.; Greve, Douglas N.; Wiggins, Graham; Wald, Lawrence L.; Belliveau, John W.

    2008-01-01

    Developments in multi-channel radio-frequency (RF) coil array technology have enabled functional magnetic resonance imaging (fMRI) with higher degrees of spatial and temporal resolution. While modest improvement in temporal acceleration has been achieved by increasing the number of RF coils, in parallel data acquisition techniques, the maximum attainable acceleration is intrinsically limited only by the amount of independent spatial information in the combined array channels. Since the geometric configuration of a large-n MRI head coil array is similar to that used in EEG electrode or MEG SQUID sensor arrays, the source localization algorithms used in MEG or EEG source imaging can be extended to also process MRI coil array data, resulting in greatly improved temporal resolution by minimizing k-space traversal during signal acquisition. Using a novel approach, we acquire multi-channel MRI head coil array data and then apply inverse reconstruction methods to obtain volumetric fMRI estimates of blood oxygenation level dependent (BOLD) contrast at unprecedented whole-brain acquisition rates of 100 ms per sample. We call this combination of techniques magnetic resonance Inverse Imaging (InI), a method that provides estimates of dynamic spatially-resolved signal change that can be used to construct statistical maps of task-related brain activity. We demonstrate the sensitivity and inter-subject reliability of volumetric InI using an event-related design to probe the hemodynamic signal modulations in primary visual cortex. Robust results from both single subject and group analyses demonstrate the sensitivity and feasibility of using volumetric InI in high temporal resolution investigations of human brain function. PMID:18538587

  1. A Miniature Magnetic-Force-Based Three-Axis AC Magnetic Sensor with Piezoelectric/Vibrational Energy-Harvesting Functions.

    PubMed

    Hung, Chiao-Fang; Yeh, Po-Chen; Chung, Tien-Kan

    2017-02-08

    In this paper, we demonstrate a miniature magnetic-force-based, three-axis, AC magnetic sensor with piezoelectric/vibrational energy-harvesting functions. For magnetic sensing, the sensor employs a magnetic-mechanical-piezoelectric configuration (which uses magnetic force and torque, a compact, single, mechanical mechanism, and the piezoelectric effect) to convert x-axis and y-axis in-plane and z-axis magnetic fields into piezoelectric voltage outputs. Under the x-axis magnetic field (sine-wave, 100 Hz, 0.2-3.2 gauss) and the z-axis magnetic field (sine-wave, 142 Hz, 0.2-3.2 gauss), the voltage output with the sensitivity of the sensor are 1.13-26.15 mV with 8.79 mV/gauss and 1.31-8.92 mV with 2.63 mV/gauss, respectively. In addition, through this configuration, the sensor can harness ambient vibrational energy, i.e., possessing piezoelectric/vibrational energy-harvesting functions. Under x-axis vibration (sine-wave, 100 Hz, 3.5 g) and z-axis vibration (sine-wave, 142 Hz, 3.8 g), the root-mean-square voltage output with power output of the sensor is 439 mV with 0.333 μW and 138 mV with 0.051 μW, respectively. These results show that the sensor, using this configuration, successfully achieves three-axis magnetic field sensing and three-axis vibration energy-harvesting. Due to these features, the three-axis AC magnetic sensor could be an important design reference in order to develop future three-axis AC magnetic sensors, which possess energy-harvesting functions, for practical industrial applications, such as intelligent vehicle/traffic monitoring, processes monitoring, security systems, and so on.

  2. Cognitive Function Related to the Sirh11/Zcchc16 Gene Acquired from an LTR Retrotransposon in Eutherians

    PubMed Central

    Irie, Masahito; Yoshikawa, Masanobu; Ono, Ryuichi; Iwafune, Hirotaka; Furuse, Tamio; Yamada, Ikuko; Wakana, Shigeharu; Yamashita, Yui; Abe, Takaya; Ishino, Fumitoshi; Kaneko-Ishino, Tomoko

    2015-01-01

    Gene targeting of mouse S ushi- i chi-related r etrotransposon h omologue 11 / Z inc finger CCHC domain-containing 16 (Sirh11/Zcchc16) causes abnormal behaviors related to cognition, including attention, impulsivity and working memory. Sirh11/Zcchc16 encodes a CCHC type of zinc-finger protein that exhibits high homology to an LTR retrotransposon Gag protein. Upon microdialysis analysis of the prefrontal cortex region, the recovery rate of noradrenaline (NA) was reduced compared with dopamine (DA) after perfusion of high potassium-containing artificial cerebrospinal fluid in knockout (KO) mice. These data indicate that Sirh11/Zcchc16 is involved in cognitive function in the brain, possibly via the noradrenergic system, in the contemporary mouse developmental systems. Interestingly, it is highly conserved in three out of the four major groups of the eutherians, euarchontoglires, laurasiatheria and afrotheria, but is heavily mutated in xenarthran species such as the sloth and armadillo, suggesting that it has contributed to brain evolution in the three major eutherian lineages, including humans and mice. Sirh11/Zcchc16 is the first SIRH gene to be involved in brain function, instead of just the placenta, as seen in the case of Peg10, Peg11/Rtl1 and Sirh7/Ldoc1. PMID:26402067

  3. Cognitive Function Related to the Sirh11/Zcchc16 Gene Acquired from an LTR Retrotransposon in Eutherians.

    PubMed

    Irie, Masahito; Yoshikawa, Masanobu; Ono, Ryuichi; Iwafune, Hirotaka; Furuse, Tamio; Yamada, Ikuko; Wakana, Shigeharu; Yamashita, Yui; Abe, Takaya; Ishino, Fumitoshi; Kaneko-Ishino, Tomoko

    2015-09-01

    Gene targeting of mouse Sushi-ichi-related retrotransposon homologue 11/Zinc finger CCHC domain-containing 16 (Sirh11/Zcchc16) causes abnormal behaviors related to cognition, including attention, impulsivity and working memory. Sirh11/Zcchc16 encodes a CCHC type of zinc-finger protein that exhibits high homology to an LTR retrotransposon Gag protein. Upon microdialysis analysis of the prefrontal cortex region, the recovery rate of noradrenaline (NA) was reduced compared with dopamine (DA) after perfusion of high potassium-containing artificial cerebrospinal fluid in knockout (KO) mice. These data indicate that Sirh11/Zcchc16 is involved in cognitive function in the brain, possibly via the noradrenergic system, in the contemporary mouse developmental systems. Interestingly, it is highly conserved in three out of the four major groups of the eutherians, euarchontoglires, laurasiatheria and afrotheria, but is heavily mutated in xenarthran species such as the sloth and armadillo, suggesting that it has contributed to brain evolution in the three major eutherian lineages, including humans and mice. Sirh11/Zcchc16 is the first SIRH gene to be involved in brain function, instead of just the placenta, as seen in the case of Peg10, Peg11/Rtl1 and Sirh7/Ldoc1.

  4. Retina specific GCAPs in zebrafish acquire functional selectivity in Ca2+-sensing by myristoylation and Mg2+-binding

    PubMed Central

    Sulmann, Stefan; Vocke, Farina; Scholten, Alexander; Koch, Karl-Wilhelm

    2015-01-01

    Zebrafish photoreceptor cells express six guanylate cyclase-activating proteins (zGCAPs) that share a high degree of amino acid sequence homology, but differ in Ca2+-binding properties, Ca2+-sensitive target regulation and spatial-temporal expression profiles. We here study a general problem in cellular Ca2+-sensing, namely how similar Ca2+-binding proteins achieve functional selectivity to control finely adjusted cellular responses. We investigated two parameters of critical importance for the trigger and switch function of guanylate cyclase-activating proteins: the myristoylation status and the occupation of Ca2+-binding sites with Mg2+. All zGCAPs can be myristoylated in living cells using click chemistry. Myristoylation does not facilitate membrane binding of zGCAPs, but it significantly modified the regulatory properties of zGCAP2 and zGCAP5. We further determined for all zGCAPs at least two binding sites exhibiting high affinities for Ca2+ with KD values in the submicromolar range, whereas for other zGCAPs (except zGCAP3) the affinity of the third binding site was in the micromolar range. Mg2+ either occupied the low affinity Ca2+-binding site or it shifted the affinities for Ca2+-binding. Hydrodynamic properties of zGCAPs are more influenced by Ca2+ than by Mg2+, although to a different extent for each zGCAP. Posttranslational modification and competing ion-binding can tailor the properties of similar Ca2+-sensors. PMID:26061947

  5. Mammalian-specific genomic functions: Newly acquired traits generated by genomic imprinting and LTR retrotransposon-derived genes in mammals

    PubMed Central

    KANEKO-ISHINO, Tomoko; ISHINO, Fumitoshi

    2015-01-01

    Mammals, including human beings, have evolved a unique viviparous reproductive system and a highly developed central nervous system. How did these unique characteristics emerge in mammalian evolution, and what kinds of changes did occur in the mammalian genomes as evolution proceeded? A key conceptual term in approaching these issues is “mammalian-specific genomic functions”, a concept covering both mammalian-specific epigenetics and genetics. Genomic imprinting and LTR retrotransposon-derived genes are reviewed as the representative, mammalian-specific genomic functions that are essential not only for the current mammalian developmental system, but also mammalian evolution itself. First, the essential roles of genomic imprinting in mammalian development, especially related to viviparous reproduction via placental function, as well as the emergence of genomic imprinting in mammalian evolution, are discussed. Second, we introduce the novel concept of “mammalian-specific traits generated by mammalian-specific genes from LTR retrotransposons”, based on the finding that LTR retrotransposons served as a critical driving force in the mammalian evolution via generating mammalian-specific genes. PMID:26666304

  6. Detection of carcinoembryonic antigen using functional magnetic and fluorescent nanoparticles in magnetic separators

    NASA Astrophysics Data System (ADS)

    Tsai, H. Y.; Chang, C. Y.; Li, Y. C.; Chu, W. C.; Viswanathan, K.; Bor Fuh, C.

    2011-06-01

    We combined a sandwich immunoassay, anti-CEA/CEA/anti-CEA, with functional magnetic ( 80 nm) and fluorescent ( 180 nm) nanoparticles in magnetic separators to demonstrate a detection method for carcinoembryonic antigen (CEA). Determination of CEA in serum can be used in clinical diagnosis and monitoring of tumor-related diseases. The CEA concentrations in samples were deduced and determined based on the reference plot using the measured fluorescent intensity of sandwich nanoparticles from the sample. The linear range of CEA detection was from 18 ng/mL to 1.8 pg/mL. The detection limit of CEA was 1.8 pg/mL. In comparison with most other detection methods, this method had advantages of lower detection limit and wider linear range. The recovery was higher than 94%. The CEA concentrations of two serum samples were determined to be 9.0 and 55 ng/mL, which differed by 6.7% (9.6 ng/mL) and 9.1% (50 ng/mL) from the measurements of enzyme-linked immunosorbent assay (ELISA), respectively. The analysis time can be reduced to one third of ELISA. This method has good potential for other biomarker detections and biochemical applications.

  7. A Hitchhiker's Guide to Functional Magnetic Resonance Imaging

    PubMed Central

    Soares, José M.; Magalhães, Ricardo; Moreira, Pedro S.; Sousa, Alexandre; Ganz, Edward; Sampaio, Adriana; Alves, Victor; Marques, Paulo; Sousa, Nuno

    2016-01-01

    Functional Magnetic Resonance Imaging (fMRI) studies have become increasingly popular both with clinicians and researchers as they are capable of providing unique insights into brain functions. However, multiple technical considerations (ranging from specifics of paradigm design to imaging artifacts, complex protocol definition, and multitude of processing and methods of analysis, as well as intrinsic methodological limitations) must be considered and addressed in order to optimize fMRI analysis and to arrive at the most accurate and grounded interpretation of the data. In practice, the researcher/clinician must choose, from many available options, the most suitable software tool for each stage of the fMRI analysis pipeline. Herein we provide a straightforward guide designed to address, for each of the major stages, the techniques, and tools involved in the process. We have developed this guide both to help those new to the technique to overcome the most critical difficulties in its use, as well as to serve as a resource for the neuroimaging community. PMID:27891073

  8. Achromatic synesthesias - a functional magnetic resonance imaging study.

    PubMed

    Melero, H; Ríos-Lago, M; Peña-Melián, A; Álvarez-Linera, J

    2014-09-01

    Grapheme-color synesthetes experience consistent, automatic and idiosyncratic colors associated with specific letters and numbers. Frequently, these specific associations exhibit achromatic synesthetic qualities (e.g. white, black or gray). In this study, we have investigated for the first time the neural basis of achromatic synesthesias, their relationship to chromatic synesthesias and the achromatic congruency effect in order to understand not only synesthetic color but also other components of the synesthetic experience. To achieve this aim, functional magnetic resonance imaging experiments were performed in a group of associator grapheme-color synesthetes and matched controls who were stimulated with real chromatic and achromatic stimuli (Mondrians), and with letters and numbers that elicited different types of grapheme-color synesthesias (i.e. chromatic and achromatic inducers which elicited chromatic but also achromatic synesthesias, as well as congruent and incongruent ones). The information derived from the analysis of Mondrians and chromatic/achromatic synesthesias suggests that real and synesthetic colors/achromaticity do not fully share neural mechanisms. The whole-brain analysis of BOLD signals in response to the complete set of synesthetic inducers revealed that the functional peculiarities of the synesthetic brain are distributed, and reflect different components of the synesthetic experience: a perceptual component, an (attentional) feature binding component, and an emotional component. Additionally, the inclusion of achromatic experiences has provided new evidence in favor of the emotional binding theory, a line of interpretation which constitutes a bridge between grapheme-color synesthesia and other developmental modalities of the phenomenon.

  9. Methodological challenges and solutions in auditory functional magnetic resonance imaging

    PubMed Central

    Peelle, Jonathan E.

    2014-01-01

    Functional magnetic resonance imaging (fMRI) studies involve substantial acoustic noise. This review covers the difficulties posed by such noise for auditory neuroscience, as well as a number of possible solutions that have emerged. Acoustic noise can affect the processing of auditory stimuli by making them inaudible or unintelligible, and can result in reduced sensitivity to auditory activation in auditory cortex. Equally importantly, acoustic noise may also lead to increased listening effort, meaning that even when auditory stimuli are perceived, neural processing may differ from when the same stimuli are presented in quiet. These and other challenges have motivated a number of approaches for collecting auditory fMRI data. Although using a continuous echoplanar imaging (EPI) sequence provides high quality imaging data, these data may also be contaminated by background acoustic noise. Traditional sparse imaging has the advantage of avoiding acoustic noise during stimulus presentation, but at a cost of reduced temporal resolution. Recently, three classes of techniques have been developed to circumvent these limitations. The first is Interleaved Silent Steady State (ISSS) imaging, a variation of sparse imaging that involves collecting multiple volumes following a silent period while maintaining steady-state longitudinal magnetization. The second involves active noise control to limit the impact of acoustic scanner noise. Finally, novel MRI sequences that reduce the amount of acoustic noise produced during fMRI make the use of continuous scanning a more practical option. Together these advances provide unprecedented opportunities for researchers to collect high-quality data of hemodynamic responses to auditory stimuli using fMRI. PMID:25191218

  10. Acquired Cystic Kidney Disease

    MedlinePlus

    ... They Work Kidney Disease A-Z Acquired Cystic Kidney Disease What is acquired cystic kidney disease? Acquired cystic kidney disease happens when a ... cysts. What are the differences between acquired cystic kidney disease and polycystic kidney disease? Acquired cystic kidney ...

  11. A Miniature Magnetic-Force-Based Three-Axis AC Magnetic Sensor with Piezoelectric/Vibrational Energy-Harvesting Functions

    PubMed Central

    Hung, Chiao-Fang; Yeh, Po-Chen; Chung, Tien-Kan

    2017-01-01

    In this paper, we demonstrate a miniature magnetic-force-based, three-axis, AC magnetic sensor with piezoelectric/vibrational energy-harvesting functions. For magnetic sensing, the sensor employs a magnetic–mechanical–piezoelectric configuration (which uses magnetic force and torque, a compact, single, mechanical mechanism, and the piezoelectric effect) to convert x-axis and y-axis in-plane and z-axis magnetic fields into piezoelectric voltage outputs. Under the x-axis magnetic field (sine-wave, 100 Hz, 0.2–3.2 gauss) and the z-axis magnetic field (sine-wave, 142 Hz, 0.2–3.2 gauss), the voltage output with the sensitivity of the sensor are 1.13–26.15 mV with 8.79 mV/gauss and 1.31–8.92 mV with 2.63 mV/gauss, respectively. In addition, through this configuration, the sensor can harness ambient vibrational energy, i.e., possessing piezoelectric/vibrational energy-harvesting functions. Under x-axis vibration (sine-wave, 100 Hz, 3.5 g) and z-axis vibration (sine-wave, 142 Hz, 3.8 g), the root-mean-square voltage output with power output of the sensor is 439 mV with 0.333 μW and 138 mV with 0.051 μW, respectively. These results show that the sensor, using this configuration, successfully achieves three-axis magnetic field sensing and three-axis vibration energy-harvesting. Due to these features, the three-axis AC magnetic sensor could be an important design reference in order to develop future three-axis AC magnetic sensors, which possess energy-harvesting functions, for practical industrial applications, such as intelligent vehicle/traffic monitoring, processes monitoring, security systems, and so on. PMID:28208693

  12. Identification of an Intracranial Pressure (ICP) Response Function from Continuously Acquired Electroencephalographic and ICP Signals in Burst-Suppressed Patients.

    PubMed

    Connolly, Mark; Liou, Raymond; Vespa, Paul; Hu, Xiao

    2016-01-01

    Continuous intracranial pressure (ICP) and electroencephalographic (EEG) monitoring are used in the management of patients with brain injury. It is possible that these two signals could be related through neurovascular coupling. To explore this mechanism, we modeled the ICP response to brain activity by treating spontaneous burst activity in burst-suppressed patients as an impulse, and identified the ICP response function (ICPRF) as the subsequent change in ICP.Segments of ICP were filtered, classified as elevating or stable, and suitable ICPRFs were identified. After calibration, each ICPRF was convolved with the EEG to produce the estimated ICP. The mean error (ME) versus distance from the selected ICPRF was calculated and the elevating and stable ICP segments compared.Eighty-four ICPRFs were identified from 15 data segments. The ME of the elevating segments increased at an average rate of 57 mmHg/min, whereas the average ME of the stable segments increased at a rate of 0.05 mmHg/min.These findings demonstrate that deriving an ICPRF from a burst-suppressed patient is a suitable approach for stable segments. To completely model the ICP response to EEG activity, a more robust model should be developed.

  13. Interleukin-35-Producing CD8α+ Dendritic Cells Acquire a Tolerogenic State and Regulate T Cell Function

    PubMed Central

    Haller, Sergio; Duval, Anaïs; Migliorini, Romain; Stevanin, Mathias; Mack, Vanessa; Acha-Orbea, Hans

    2017-01-01

    Dendritic cells (DCs) play a central role in shaping immunogenic as well as tolerogenic adaptive immune responses and thereby dictate the outcome of adaptive immunity. Here, we report the generation of a CD8α+ DC line constitutively secreting the tolerogenic cytokine interleukin (IL)-35. IL-35 secretion led to impaired CD4+ and CD8+ T lymphocyte proliferation and interfered with their function in vitro and also in vivo. IL-35 was furthermore found to induce a tolerogenic phenotype on CD8α+ DCs, characterized by the upregulation of CD11b, downregulation of MHC class II, a reduced costimulatory potential as well as production of the immunomodulatory molecule IL-10. Vaccination of mice with IL-35-expressing DCs promoted tumor growth and reduced the severity of autoimmune encephalitis not only in a preventive but also after induction of encephalitogenic T cells. The reduction in experimental autoimmune encephalitis severity was significantly more pronounced when antigen-pulsed IL-35+ DCs were used. These findings suggest a new, indirect effector mechanism by which IL-35-responding antigen-presenting cells contribute to immune tolerance. Furthermore, IL-35-transfected DCs may be a promising approach for immunotherapy in the context of autoimmune diseases. PMID:28228759

  14. Neurocognitive functioning in a Romanian cohort of young adults with parenterally-acquired HIV-infection during childhood

    PubMed Central

    Franklin, Donald R.; Burlacu, Ruxandra; Luca, Anca E.; Blaglosov, Andreea G.; Ellis, Ronald J.; Alexander, Terry J.; Umlauf, Anya; Grant, Igor; Duiculescu, Dan C.; Achim, Cristian L.; Marcotte, Thomas D.

    2015-01-01

    The Romanian cohort can provide valuable information about the effect of chronic HIV-infection and exposure to combined antiretroviral therapy (cART) on the developing brain, based on its unique characteristics: young adults infected parenterally with HIV clade F in the late 1980s and exposed to cART for a decade. We conducted a prospective study using a neuropsychological test battery validated in other international HIV cohorts, in order to evaluate the rate and severity of neurocognitive impairment in a group of young Romanian adults. The 49 HIV-infected (HIV+) participants and the 20 HIV negative (HIV−) controls were similar for age and gender, although the HIV− group tended to be more educated. We found higher cognitive impairment prevalence in the HIV+ group (59.1 %) versus the HIV− group (10 %), and the impairment rate remained significantly higher even when the groups were matched based on the educational level (38.7 % for the HIV+ group vs. 10.0 % for the HIV− controls; p=0.025). The nadir CD4 count was <200 in 71.4 % of patients, but at the time of neurocognitive assessment, 89.5 % of patients had normal immunological status and 81.8 % undetectable HIV load. Among the HIV-impaired group, 26 % of the participants had syndromic impairment while the other 74 % had asymptomatic neurocognitive impairment. We found a high prevalence of neurocognitive dysfunction in the Romanian young adults growing-up with HIV. The greatest HIV-related cognitive deficits were in the domains of executive and motor functioning, consistent with a frontosubcortical pattern. PMID:25185868

  15. [Magnetic micro-/nano-materials: functionalization and their applications in pretreatment for food samples].

    PubMed

    Gao, Qiang; Feng, Yuqi

    2014-10-01

    Magnetic solid phase extraction technique, based on functional magnetic materials, is currently a hot topic in the separation and analysis of complex samples. This paper reviews the reported methods for the functionalization of magnetic micro-/nano-materials, such as sur- face grafting organic groups, coating carbon or inorganic oxide, grafting or coating polymer, being loaded to the surface or pores of supports, being introduced into the skeleton of sup- ports, and physically co-mixing methods. Moreover, we briefly introduce the applications of the functional magnetic micro-/nano-materials in pretreatment for food samples.

  16. Rehabilitation of Executive Functions in Patients with Chronic Acquired Brain Injury with Goal Management Training, External Cuing, and Emotional Regulation: A Randomized Controlled Trial.

    PubMed

    Tornås, Sveinung; Løvstad, Marianne; Solbakk, Anne-Kristin; Evans, Jonathan; Endestad, Tor; Hol, Per Kristian; Schanke, Anne-Kristine; Stubberud, Jan

    2016-04-01

    Executive dysfunction is a common consequence of acquired brain injury (ABI), causing significant disability in daily life. This randomized controlled trial investigated the efficacy of Goal Management Training (GMT) in improving executive functioning in patients with chronic ABI. Seventy patients with a verified ABI and executive dysfunction were randomly allocated to GMT (n=33) or a psycho-educative active control condition, Brain Health Workshop (BHW) (n=37). In addition, all participants received external cueing by text messages. Neuropsychological tests and self-reported questionnaires of executive functioning were administered pre-intervention, immediately after intervention, and at 6 months follow-up. Assessors were blinded to group allocation. Questionnaire measures indicated significant improvement of everyday executive functioning in the GMT group, with effects lasting at least 6 months post-treatment. Both groups improved on the majority of the applied neuropsychological tests. However, improved performance on tests demanding executive attention was most prominent in the GMT group. The results indicate that GMT combined with external cueing is an effective metacognitive strategy training method, ameliorating executive dysfunction in daily life for patients with chronic ABI. The strongest effects were seen on self-report measures of executive functions 6 months post-treatment, suggesting that strategies learned in GMT were applied and consolidated in everyday life after the end of training. Furthermore, these findings show that executive dysfunction can be improved years after the ABI.

  17. Identification of human brain regions underlying responses to resistive inspiratory loading with functional magnetic resonance imaging.

    PubMed Central

    Gozal, D; Omidvar, O; Kirlew, K A; Hathout, G M; Hamilton, R; Lufkin, R B; Harper, R M

    1995-01-01

    Compensatory ventilatory responses to increased inspiratory loading are essential for adequate breathing regulation in a number of pulmonary diseases; however, the human brain sites mediating such responses are unknown. Midsagittal and axial images were acquired in 11 healthy volunteers during unloaded and loaded (30 cmH2O; 1 cmH2O = 98 Pa) inspiratory breathing, by using functional magnetic resonance imaging (fMRI) strategies (1.5-tesla MR; repetition time, 72 msec; echo time, 45 msec; flip angle, 30 degrees; field of view, 26 cm; slice thickness, 5 mm; number of excitations, 1; matrix, 128 x 256). Digital image subtractions and region of interest analyses revealed significantly increased fMRI signal intensity in discrete areas of the ventral and dorsal pons, interpeduncular nucleus, basal forebrain, putamen, and cerebellar regions. Upon load withdrawal, certain regions displayed a rapid fMRI signal off-transient, while in others, a slower fMRI signal decay emerged. Sustained loading elicited slow decreases in fMRI signal across activated regions, while second application of an identical load resulted in smaller signal increases compared to initial signal responses (P < 0.001). A moderate inspiratory load is associated with consistent regional activation of discrete brain locations; certain of these regions have been implicated in mediation of loaded breathing in animal models. We speculate that temporal changes in fMRI signal may indicate respiratory after-discharge and/or habituation phenomena. Images Fig. 1 Fig. 3 PMID:7604040

  18. Investigation of the structure and lithology of bedrock concealed by basin fill, using ground-based magnetic-field-profile data acquired in the San Rafael Basin, southeastern Arizona

    USGS Publications Warehouse

    Bultman, Mark W.

    2013-01-01

    Data on the Earth’s total-intensity magnetic field acquired near ground level and at measurement intervals as small as 1 m include information on the spatial distribution of nearsurface magnetic dipoles that in many cases are unique to a specific lithology. Such spatial information is expressed in the texture (physical appearance or characteristics) of the data at scales of hundreds of meters to kilometers. These magnetic textures are characterized by several descriptive statistics, their power spectrum, and their multifractal spectrum. On the basis of a graphical comparison and textural characterization, ground-based magnetic-field profile data can be used to estimate bedrock lithology concealed by as much as 100 m of basin fill in some cases, information that is especially important in assessing and exploring for concealed mineral deposits. I demonstrate that multifractal spectra of ground-based magnetic-field-profile data can be used to differentiate exposed lithologies and that the shape and position of the multifractal spectrum of the ground-based magnetic-field-profile of concealed lithologies can be matched to the upward-continued multifractal spectrum of an exposed lithology to help distinguish the concealed lithology. In addition, ground-based magnetic-field-profile data also detect minute differences in the magnetic susceptibility of rocks over small horizontal and vertical distances and so can be used for precise modeling of bedrock geometry and structure, even when that bedrock is concealed by 100 m or more of nonmagnetic basin fill. Such data contain valuable geologic information on the bedrock concealed by basin fill that may not be so visible in aeromagnetic data, including areas of hydrothermal alteration, faults, and other bedrock structures. Interpretation of these data in the San Rafael Basin, southeastern Arizona, has yielded results for estimating concealed lithologies, concealed structural geology, and a concealed potential mineral

  19. [Functional magnetic resonance imaging and dynamic neuroanatomy of addictive disorders].

    PubMed

    Mel'nikov, M E; Shtark, M B

    2014-01-01

    Research into the cerebral patterns that govern the formation and development of addictive behavior is one of the most interesting goals of neurophysiology. Authors of contemporary papers on the matter define a number of symptoms that are all part of substance or non-substance dependence, each one of them leading to abnormalities in the corresponding system of the brain. During the last twenty years the functional magnetic resonance imaging (fMR1) technology has been instrumental in locating such abnormalities, identifying specific parts of the brain that, when dysfunctional, may enhance addiction and cause its positive or negative symptoms. This article reviews fMRI studies aimed toward locating areas in the brain that are responsible for cognitive, emotional, and motivational dysfunction. Cerebral correlatives of impulsiveness, behavior control, and drug cravings are reviewed separately. The article also contains an overview of possibilities to further investigate the Selves of those dependent on substances, identify previously unknown diagnostic markers of substance dependence, and evaluate the effectiveness of therapy. The research under review in this article provides data that points to a special role of the nucleus caudatus as well as the nucleus accumbens, the thalamus, the insular cortex (IC), the anterior cingulate, prefrontal and orbitofrontal areas in psychological disorders that are part of substance dependence. General findings of the article are in accordance with contemporary models of addictive pattern.

  20. Multi-function magnetic jack control drive mechanism

    DOEpatents

    Bollinger, L.R.; Crawford, D.C.

    1983-10-06

    A multi-function magnetic jack control drive mechanism for controlling a nuclear reactor is provided. The mechanism includes an elongate pressure housing in which a plurality of closely spaced drive rods are located. Each drive rod is connected to a rod which is insertable in the reactor core. An electromechanical stationary latch device is provided which is actuatable to hold each drive rod stationary with respect to the pressure housing. An electromechanical movable latch device is also provided for each one of the drive rods. Each movable latch device is provided with a base and is actuatable to hold a respective drive rod stationary with respect to the base. An electromechanical lift device is further provided for each base which is actuatable for moving a respective base longitudinally along the pressure housing. In this manner, one or more drive rods can be moved in the pressure housing by sequentially and repetitively operating the electromechanical devices. Preferably, each latch device includes a pair of opposed latches which grip teeth located on the respective drive rod. Two, three, or four drive rods can be located symmetrically about the longitudinal axis of the pressure housing.

  1. Multi-function magnetic jack control drive mechanism

    DOEpatents

    Bollinger, Lawrence R.; Crawford, Donald C.

    1986-01-01

    A multi-function magnetic jack control drive mechanism for controlling a nuclear reactor is provided. The mechanism includes an elongate pressure housing in which a plurality of closely spaced drive rods are located. Each drive rod is connected to a rod which is insertable in the reactor core. An electromechanical stationary latch device is provided which is actuatable to hold each drive rod stationary with respect to the pressure housing. An electromechanical movable latch device is also provided for each one of the drive rods. Each movable latch device is provided with a base and is actuatable to hold a respective drive rod stationary with respect to the base. An electromechanical lift device is further provided for each base which is actuatable for moving a respective base longitudinally along the pressure housing. In this manner, one or more drive rods can be moved in the pressure housing by sequentially and repetitively operating the electromechanical devices. Preferably, each latch device includes a pair of opposed latches which grip teeth located on the respective drive rod. Two, three, or four drive rods can be located symmetrically about the longitudinal axis of the pressure housing.

  2. One-step ligand exchange reaction as an efficient way for functionalization of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Mrówczyński, Radosław; Rednic, Lidia; Turcu, Rodica; Liebscher, Jürgen

    2012-07-01

    Novel magnetic Fe3O4 nanoparticles (NPs) covered by one layer of functionalized fatty acids, bearing entities (Hayashi catalyst, biotin, quinine, proline, and galactose) of high interest for practical application in nanomedicine or organocatalysis, were synthesized. The functionalized fatty acids were obtained by Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) of azido fatty acids with alkynes. All the magnetic NPs show superparamagnetic behavior with high values of magnetization and high colloidal stability in DCM solution.

  3. Multimodality evaluation of ventricular function: comparison of cardiac magnetic resonance imaging, echocardiography, and planar and SPECT blood pool imaging

    NASA Astrophysics Data System (ADS)

    Feiglin, David H.; Krol, Andrzej; Tillapaugh-Fay, Gwen M.; Szeverenyi, Nikolaus M.; Thomas, Frank D.

    2001-05-01

    Fifteen patients underwent resting echocardiography (EC), ECG gated cardiac MR ventriculography (MRV) and blood pool planar and SPECT ventriculography (SPV) sequentially on the same day. In addition, 36 patients had sequential ECG gated blood pool and SPV and 20 normal volunteers, age > 18 years, had sequential ECG gated cardiac MRI performed on both Siemens closed, 1.5T, and open, 0.2T, magnets. Echocardiography was performed using a HP 5500 system equipped with an S4 transducer in 2D mode. MRV at 0.2T and 1.5T used a circular polarized body coil. Nuclear Medicine studies used 25 mCi Tc- 99m labeled red blood cells. Gated planar and SPV were acquired on a dual head Siemens E-Cam system. We have found that MRV affords the most accurate measurement of ventricular function. SPV and MRV provide similar estimations of left ventricular function (LVEF). Further, SPV consistently provides higher LVEF, as compared to the planar data simultaneously acquired. Observed significant differences in intermodality measurements indicate that follow up studies in patients, especially in patients whose management is critically dependent on functional measurement changes, should be monitored by one modality only.

  4. Neuronal correlates of functional magnetic resonance imaging in human temporal cortex

    PubMed Central

    Corina, David P.; Corrigan, Neva; Schoenfield-McNeill, Julie; Poliakov, Andrew; Zamora, Leona; Zanos, Stavros

    2010-01-01

    The relationship between changes in functional magnetic resonance imaging and neuronal activity remains controversial. Data collected during awake neurosurgical procedures for the treatment of epilepsy provided a rare opportunity to examine this relationship in human temporal association cortex. We obtained functional magnetic resonance imaging blood oxygen dependent signals, single neuronal activity and local field potentials from 8 to 300 Hz at 13 temporal cortical sites, from nine subjects, during paired associate learning and control measures. The relation between the functional magnetic resonance imaging signal and the electrophysiologic parameters was assessed in two ways: colocalization between significant changes in these signals on the same paired associate-control comparisons and multiple linear regressions of the electrophysiologic measures on the functional magnetic resonance imaging signal, across all tasks. Significant colocalization was present between increased functional magnetic resonance imaging signals and increased local field potentials power in the 50–250 Hz range. Local field potentials power greater than 100 Hz was also a significant regressor for the functional magnetic resonance imaging signal, establishing this local field potentials frequency range as a neuronal correlate of the functional magnetic resonance imaging signal. There was a trend for a relation between power in some low frequency local field potentials frequencies and the functional magnetic resonance imaging signal, for 8–15 Hz increases in the colocalization analysis and 16–23 Hz in the multiple linear regression analysis. Neither analysis provided evidence for an independent relation to frequency of single neuron activity. PMID:19773355

  5. Collimator Magnet with Functionally Defined Profile for Ion Implantation

    SciTech Connect

    Nicolaescu, Dan; Gotoh, Yasuhito; Sakai, Shigeki; Ishikawa, Junzo

    2011-01-07

    Advanced implantation systems used for semiconductor processing should have high precision of ion beam collimation (+/-0.1 deg and better) and wide beam aperture (400 mm and more). Typical arrangements of ion implantation systems include beam scanning (BSM) and collimator magnets (CM). Standard collimator magnets have limited precision of beam collimation due to magnetic poles that have piecewise circular profile. This study proposes a novel ''constant sum angle collimator magnet''(CSACM) with non-circular magnetic pole profile. Angles of incidence {alpha}{sub i} and exit {alpha}{sub e} are defined as angles between ion trajectory and local normal to CM input/output magnetic pole edge. Profile of the CSACM is defined as having constant algebraic sum {alpha}{sub i}+{alpha}{sub e} = const for every ion trajectory of the scanned beam, in addition to ''usual'' beam collimation. An iterative procedure allows improve CSACM taking into account magnetic fringe field effects. Simulation results prove that CSACM assures precise beam collimation in two orthogonal planes. Circular approximations for CSACM magnetic poles are proposed. The model may be further developed for global design of the ion beam line (BSM+CM) and for taking into account space-charge effects.

  6. [Participation limitations following acquired brain damage: a pilot study on the relationship among functional disorders as well as personal and environmental context factors].

    PubMed

    Fries, W; Fischer, S

    2008-10-01

    The SGB IX, book 9 of the German social code (Sozialgesetzbuch, SGB), which is the legal basis of rehabilitation in Germany, states "participation and self-determined conduct of life" as the ultimate ambition of rehabilitation. This concept of participation and disability is based on the WHO model expressed in the International Classification of Functioning, Disability and Health (ICF). In this model, participation after the onset of a health problem may not only be infringed by disturbances in body functions and structures and the resulting activity limitations but also by contextual factors such as environmental and personal factors. In an outpatient neurological rehabilitation centre we prospectively rated for 49 patients the influence of these contextual factors as well as of objectively assessed functional/activity limitations on the overall disability. On average, functional/activity limitations were rated as contributing 58.4% (SD=17.2%), personal factors 26.4% (SD=12.7%) and environmental factors 15.1% (SD=11.2%) to the overall disability. The functional/activity limitations closely matched the expected limitations based on the underlying brain lesions. The degree of disability based on contextual factors was not related to activity limitations based on disturbances of body functions and structures. Also, demographic variables such as age, sex or chronicity were not significantly linked to contextual factors. Since contextual factors together contributed 41.6% (SD=17.2%) to the overall disability they have major relevance for the rehabilitation process, because they essentially decide on the extent to which abilities acquired by the rehabilitant during rehabilitation actually be transfered to his everyday life. Therefore, rehabilitation programmes need to include assessment and treatment of contextual factors. It hence is necessary to develop instruments to quantify contextual factors.

  7. Dissociations between behavioural and functional magnetic resonance imaging-based evaluations of cognitive function after brain injury.

    PubMed

    Bardin, Jonathan C; Fins, Joseph J; Katz, Douglas I; Hersh, Jennifer; Heier, Linda A; Tabelow, Karsten; Dyke, Jonathan P; Ballon, Douglas J; Schiff, Nicholas D; Voss, Henning U

    2011-03-01

    Functional neuroimaging methods hold promise for the identification of cognitive function and communication capacity in some severely brain-injured patients who may not retain sufficient motor function to demonstrate their abilities. We studied seven severely brain-injured patients and a control group of 14 subjects using a novel hierarchical functional magnetic resonance imaging assessment utilizing mental imagery responses. Whereas the control group showed consistent and accurate (for communication) blood-oxygen-level-dependent responses without exception, the brain-injured subjects showed a wide variation in the correlation of blood-oxygen-level-dependent responses and overt behavioural responses. Specifically, the brain-injured subjects dissociated bedside and functional magnetic resonance imaging-based command following and communication capabilities. These observations reveal significant challenges in developing validated functional magnetic resonance imaging-based methods for clinical use and raise interesting questions about underlying brain function assayed using these methods in brain-injured subjects.

  8. Studies in nonlinear optics and functional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Dai, Tehui

    There are two parts in this thesis. The first part will involve a study in the anomalous dispersion phase matched second-harmonic generation, and the second part will be a study in functional magnetic resonance imaging (fMRI) and a biophysical model of the human muscle. In part I, we report on a series of tricyanovinylaniline chromophores for use as dopants in poled poly(methyl methacrylate) waveguides for anomalous-dispersion phase- matched second-harmonic generation. Second-harmonic generation measurements as a function of mode index confirmed anomalous dispersion phase-matching efficiencies as large as 245%/Wcm2 over a propagation length of ~35 μm. The waveguide coupling technique limited the interaction length. The photostability of the chromophores was measured directly and found to agree qualitatively with second-harmonic measurements over time and was found to be improved over previously reported materials. In part II, we designed a system that could record joint force and surface electromyography (EMG) simultaneously with fMRI data. I-Egh quality force and EMG data were obtained at the same time that excellent fMRI brain images were achieved. Using this system we determined the relationship between the fMRI-measured brain activation and the handgrip force, and between the fMRI-measured brain activation and the EMG of finger flexor muscles. We found that in the whole brain and in the majority of motor function-related cortical fields, the degree of muscle activation is directly proportional to the amplitude of the brain signal determined by the fMRI measurement. The similarity in the relationship between muscle output and fMRI signal in a number of brain areas suggests that multiple cortical fields are involved in controlling muscle force. The factors that may contribute to the fMRI signals are discussed. A biophysical twitch force model was developed to predict force response under electrical stimulation. Comparison between experimental and modeled force

  9. Magnetic nanoparticles: synthesis, functionalization, and applications in bioimaging and magnetic energy storage

    PubMed Central

    Frey, Natalie A.; Peng, Sheng; Cheng, Kai; Sun, Shouheng

    2009-01-01

    This tutorial review summarizes the recent advances in the chemical synthesis and potential applications of monodisperse magnetic nanoparticles. After a brief introduction to nanomagnetism, the review focuses on recent developments in solution phase syntheses of monodisperse MFe2O4, Co, Fe, CoFe, FePt and SmCo5 nanoparticles. The review further outlines the surface, structural, and magnetic properties of these nanoparticles for biomedicine and magnetic energy storage applications. PMID:19690734

  10. Cardiovascular risks and brain function: a functional magnetic resonance imaging study of executive function in older adults.

    PubMed

    Chuang, Yi-Fang; Eldreth, Dana; Erickson, Kirk I; Varma, Vijay; Harris, Gregory; Fried, Linda P; Rebok, George W; Tanner, Elizabeth K; Carlson, Michelle C

    2014-06-01

    Cardiovascular (CV) risk factors, such as hypertension, diabetes, and hyperlipidemia are associated with cognitive impairment and risk of dementia in older adults. However, the mechanisms linking them are not clear. This study aims to investigate the association between aggregate CV risk, assessed by the Framingham general cardiovascular risk profile, and functional brain activation in a group of community-dwelling older adults. Sixty participants (mean age: 64.6 years) from the Brain Health Study, a nested study of the Baltimore Experience Corps Trial, underwent functional magnetic resonance imaging using the Flanker task. We found that participants with higher CV risk had greater task-related activation in the left inferior parietal region, and this increased activation was associated with poorer task performance. Our results provide insights into the neural systems underlying the relationship between CV risk and executive function. Increased activation of the inferior parietal region may offer a pathway through which CV risk increases risk for cognitive impairment.

  11. Cavernosal nerve functionality evaluation after magnetic resonance imaging-guided transurethral ultrasound treatment of the prostate

    PubMed Central

    Sammet, Steffen; Partanen, Ari; Yousuf, Ambereen; Sammet, Christina L; Ward, Emily V; Wardrip, Craig; Niekrasz, Marek; Antic, Tatjana; Razmaria, Aria; Farahani, Keyvan; Sokka, Shunmugavelu; Karczmar, Gregory; Oto, Aytekin

    2015-01-01

    AIM: To evaluate the feasibility of using therapeutic ultrasound as an alternative treatment option for organ-confined prostate cancer. METHODS: In this study, a trans-urethral therapeutic ultrasound applicator in combination with 3T magnetic resonance imaging (MRI) guidance was used for real-time multi-planar MRI-based temperature monitoring and temperature feedback control of prostatic tissue thermal ablation in vivo. We evaluated the feasibility and safety of MRI-guided trans-urethral ultrasound to effectively and accurately ablate prostate tissue while minimizing the damage to surrounding tissues in eight canine prostates. MRI was used to plan sonications, monitor temperature changes during therapy, and to evaluate treatment outcome. Real-time temperature and thermal dose maps were calculated using the proton resonance frequency shift technique and were displayed as two-dimensional color-coded overlays on top of the anatomical images. After ultrasound treatment, an evaluation of the integrity of cavernosal nerves was performed during prostatectomy with a nerve stimulator that measured tumescence response quantitatively and indicated intact cavernous nerve functionality. Planned sonication volumes were visually correlated to MRI ablation volumes and corresponding histo-pathological sections after prostatectomy. RESULTS: A total of 16 sonications were performed in 8 canines. MR images acquired before ultrasound treatment were used to localize the prostate and to prescribe sonication targets in all canines. Temperature elevations corresponded within 1 degree of the targeted sonication angle, as well as with the width and length of the active transducer elements. The ultrasound treatment procedures were automatically interrupted when the temperature in the target zone reached 56 °C. In all canines erectile responses were evaluated with a cavernous nerve stimulator post-treatment and showed a tumescence response after stimulation with an electric current. These

  12. Lectin-functionalized magnetic iron oxide nanoparticles for reproductive improvement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Semen ejaculates contain heterogeneous sperm populations that can jeopardize male fertility. Recent development of nanotechnology in physiological systems may have applications in reproductive biology. Here, we used magnetic nanoparticles as a novel strategy for sperm purification to imp...

  13. Biomedical Applications of Magnetically Functionalized Organic/Inorganic Hybrid Nanofibers

    PubMed Central

    Lee, Hwa-Jeong; Lee, Sang Joon; Uthaman, Saji; Thomas, Reju George; Hyun, Hoon; Jeong, Yong Yeon; Cho, Chong-Su; Park, In-Kyu

    2015-01-01

    Nanofibers are one-dimensional nanomaterial in fiber form with diameter less than 1 µm and an aspect ratio (length/diameter) larger than 100:1. Among the different types of nanoparticle-loaded nanofiber systems, nanofibers loaded with magnetic nanoparticles have gained much attention from biomedical scientists due to a synergistic effect obtained from the unique properties of both the nanofibers and magnetic nanoparticles. These magnetic nanoparticle-encapsulated or -embedded nanofiber systems can be used not only for imaging purposes but also for therapy. In this review, we focused on recent advances in nanofibers loaded with magnetic nanoparticles, their biomedical applications, and future trends in the application of these nanofibers. PMID:26084046

  14. 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.

  15. Non-perturbative calculation of molecular magnetic properties within current-density functional theory.

    PubMed

    Tellgren, E I; Teale, A M; Furness, J W; Lange, K K; Ekström, U; Helgaker, T

    2014-01-21

    We present a novel implementation of Kohn-Sham density-functional theory utilizing London atomic orbitals as basis functions. External magnetic fields are treated non-perturbatively, which enable the study of both magnetic response properties and the effects of strong fields, using either standard density functionals or current-density functionals-the implementation is the first fully self-consistent implementation of the latter for molecules. Pilot applications are presented for the finite-field calculation of molecular magnetizabilities, hypermagnetizabilities, and nuclear magnetic resonance shielding constants, focusing on the impact of current-density functionals on the accuracy of the results. Existing current-density functionals based on the gauge-invariant vorticity are tested and found to be sensitive to numerical details of their implementation. Furthermore, when appropriately regularized, the resulting magnetic properties show no improvement over standard density-functional results. An advantage of the present implementation is the ability to apply density-functional theory to molecules in very strong magnetic fields, where the perturbative approach breaks down. Comparison with high accuracy full-configuration-interaction results show that the inadequacies of current-density approximations are exacerbated with increasing magnetic field strength. Standard density-functionals remain well behaved but fail to deliver high accuracy. The need for improved current-dependent density-functionals, and how they may be tested using the presented implementation, is discussed in light of our findings.

  16. Bacterial Nanocellulose Magnetically Functionalized for Neuro-Endovascular Treatment.

    PubMed

    Echeverry-Rendon, Mónica; Reece, Lisa M; Pastrana, Fernando; Arias, Sandra L; Shetty, Akshath R; Pavón, Juan Jose; Allain, Jean Paul

    2017-01-24

    Current treatments for brain aneurysms are invasive, traumatic, and not suitable in most patients with increased risks. A new alternative method is using scaffold stents to create a local and focal attraction force of cells for an in situ reconstruction of the tunica media. For this purpose, a nanostructured bioactive coating is designed to render an asymmetric region of the stent scaffold magnetic and biomimetic, which utilizes bacterial nanocellulose (BNC) as a platform for both magnetic and cell attraction as well as proliferation. The magnetization of the BNC is realized through the reaction of Fe III and II, precipitating superparamagnetic iron oxide nanoparticles (SPION). Subsequently, magnetic bacterial nanocellulose (MBNC) is coated with polyethylene glycol to improve its biocompatibility. Cytotoxicity and biocompatibility are evaluated using porcine aortic smooth muscle cells. Preliminary cellular migration assays demonstrate the behavior between MBNC and cells labeled with SPION. In this work, (1) synthesis of BNC impregnated with magnetic nanoparticles is successfully demonstrated; (2) a viable, resilient, and biocompatible hydrogel membrane is tested for neuroendovascular application using a stent scaffold; (3) cell viability and minimal cytotoxicity is achieved; (4) cell migration tests and examination of cellular magnetic attraction confirm the viability of MBNC as a multifunctional coating.

  17. Simulation of the modulation transfer function dependent on the partial Fourier fraction in dynamic contrast enhancement magnetic resonance imaging.

    PubMed

    Takatsu, Yasuo; Ueyama, Tsuyoshi; Miyati, Tosiaki; Yamamura, Kenichirou

    2016-12-01

    The image characteristics in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) depend on the partial Fourier fraction and contrast medium concentration. These characteristics were assessed and the modulation transfer function (MTF) was calculated by computer simulation. A digital phantom was created from signal intensity data acquired at different contrast medium concentrations on a breast model. The frequency images [created by fast Fourier transform (FFT)] were divided into 512 parts and rearranged to form a new image. The inverse FFT of this image yielded the MTF. From the reference data, three linear models (low, medium, and high) and three exponential models (slow, medium, and rapid) of the signal intensity were created. Smaller partial Fourier fractions, and higher gradients in the linear models, corresponded to faster MTF decline. The MTF more gradually decreased in the exponential models than in the linear models. The MTF, which reflects the image characteristics in DCE-MRI, was more degraded as the partial Fourier fraction decreased.

  18. Multimodal magnetic resonance imaging: The coordinated use of multiple, mutually informative probes to understand brain structure and function.

    PubMed

    Hao, Xuejun; Xu, Dongrong; Bansal, Ravi; Dong, Zhengchao; Liu, Jun; Wang, Zhishun; Kangarlu, Alayar; Liu, Feng; Duan, Yunsuo; Shova, Satie; Gerber, Andrew J; Peterson, Bradley S

    2013-02-01

    Differing imaging modalities provide unique channels of information to probe differing aspects of the brain's structural or functional organization. In combination, differing modalities provide complementary and mutually informative data about tissue organization that is more than their sum. We acquired and spatially coregistered data in four MRI modalities--anatomical MRI, functional MRI, diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS)--from 20 healthy adults to understand how interindividual variability in measures from one modality account for variability in measures from other modalities at each voxel of the brain. We detected significant correlations of local volumes with the magnitude of functional activation, suggesting that underlying variation in local volumes contributes to individual variability in functional activation. We also detected significant inverse correlations of NAA (a putative measure of neuronal density and viability) with volumes of white matter in the frontal cortex, with DTI-based measures of tissue organization within the superior longitudinal fasciculus, and with the magnitude of functional activation and default-mode activity during simple visual and motor tasks, indicating that substantial variance in local volumes, white matter organization, and functional activation derives from an underlying variability in the number or density of neurons in those regions. Many of these imaging measures correlated with measures of intellectual ability within differing brain tissues and differing neural systems, demonstrating that the neural determinants of intellectual capacity involve numerous and disparate features of brain tissue organization, a conclusion that could be made with confidence only when imaging the same individuals with multiple MRI modalities.

  19. Lateralizing language function with pre-operative functional magnetic resonance imaging in early proficient bilingual patients.

    PubMed

    Połczyńska, Monika M; Japardi, Kevin; Bookheimer, Susan Y

    2017-03-23

    Research on bilinguals with brain lesions is complicated by high patient variability, making it difficult to find well-matched controls. We benefitted from a database of over 700 patients and conducted an analysis of pre-operative functional magnetic resonance imaging data to assess language dominance in 25 early, highly proficient Spanish-English bilinguals, and 25 carefully matched monolingual controls. Our results showed that early bilingualism is associated with greater bilateral hemispheric involvement, and monolingualism is associated with stronger left hemisphere lateralization (p=0.009). The bilinguals showed more pronounced right hemisphere activation (p=0.008). Although language dominance values were concordant in the bilingual group, there were a few (12%) atypical cases with different lateralization patterns in L1 and L2. Finally, we found distinct areas of activity in first and second language within the language network, in addition to regions of convergence. These data underscore the need to map all languages proficiently spoken by surgical candidates.

  20. Functionalization and magnetization of carbon nanotubes using Co-60 gamma-ray irradiation

    NASA Astrophysics Data System (ADS)

    Chen, C. Y.; Fu, M. J.; Tsai, C. Y.; Lin, F. H.; Chen, K. Y.

    2014-10-01

    Functionalized magnetic carbon nanotubes (CNTs) can be used in the biological and biomedical fields as biosensors, drug delivery systems, etc., which makes research into processes for manufacturing modified CNTs quite important. In this paper, Co-60 gamma irradiation is shown to be an effective tool for fabricating functionalized and magnetized CNTs. After the Co-60 gamma irradiation, the presence of carboxylic functional groups on the CNT walls was confirmed by their Fourier transform infrared spectra, and the presence of Fe3O4 was verified by the X-ray diffraction patterns. The functionalized and magnetized CNTs produced using Co-60 gamma irradiation have excellent dispersion properties. The techniques for functionalizing and magnetizing CNTs are introduced in this paper, and applications of the modified CNTs will be reported after more data are gathered.

  1. Modeling drug release from functionalized magnetic nanoparticles actuated by non-heating low frequency magnetic field

    NASA Astrophysics Data System (ADS)

    Golovin, Y.; Golovin, D.; Klyachko, N.; Majouga, A.; Kabanov, A.

    2017-02-01

    Various plausible acceleration mechanisms of drug release from nanocarriers composed of a single-domain magnetic nanoparticle core with attached long macromolecule chains activated by low frequency non-heating alternating magnetic field (AMF) are discussed. The most important system characteristics affecting the AMF exposure impact are determined. Impact of several reasonable mechanisms is estimated analytically or obtained using numerical modeling. Some conditions providing manifold release acceleration as a result from exposure in AMF are found.

  2. Thigh muscle function in stroke patients revealed by velocity-encoded cine phase-contrast magnetic resonance imaging.

    PubMed

    Wen, Hongmei; Dou, Zulin; Finni, Taija; Havu, Marko; Kang, Zhuang; Cheng, Shumei; Sipilä, Sarianna; Sinha, Shantanu; Usenius, Jussi-Pekka; Cheng, Sulin

    2008-06-01

    Current methods of clinical assessment of muscle coordination and function after stroke do not provide information on deep muscles. The objective of this study was to examine how stroke affects both superficial and deep muscles' coordination and whether muscle function improves after rehabilitation. Muscle function, coordination, and activity of quadriceps femoris (QF) and hamstrings were evaluated in 10 stroke patients with mild hemiparesis and in 6 controls using velocity-encoded cine phase-contrast magnetic resonance imaging (VE-PC MRI), surface electromyography (sEMG), and maximal voluntary isometric contraction torque (MVC). At baseline, the peak muscle velocity of the rectus femoris (RF) and the ratio between the peak velocities of the RF and vasti were lower in the affected limb (AL) of stroke patients than in controls. Co-contraction of agonists and antagonists was higher in the AL than in controls. Muscle activity measured by sEMG showed similar behavior. After rehabilitation, the activity ratio of hamstrings and adductors to QF decreased slightly toward normal so there were no significant differences between the AL and controls. Impaired biarticular RF muscle function in stroke patients is the limiting factor during knee extension-flexion movements. After rehabilitation, improved functional performance was partly explained by the fact that the activities of the RF and vasti became more synchronized. VE-PC MRI can provide quantitative in vivo measurements of both superficial and deep muscles, and the information acquired after stroke can be utilized to render therapy more efficient and individually tailored.

  3. Magnetic and antimagnetic rotation in covariant density functional theory

    SciTech Connect

    Zhao, P. W.; Liang, H. Z.; Peng, J.; Ring, P.; Zhang, S. Q.; Meng, J.

    2012-10-20

    Progress on microscopic and self-consistent description of the magnetic rotation and antimagnetic rotation phenomena in tilted axis cranking relativistic mean-field theory based on a point-coupling interaction are briefly reviewed. In particular, the microscopic pictures of the shears mechanism in {sup 60}Ni and the two shears-like mechanism in {sup 105}Cd are discussed.

  4. Low-pathogenicity Mycoplasma spp. alter human monocyte and macrophage function and are highly prevalent among patients with ventilator-acquired pneumonia

    PubMed Central

    Nolan, T J; Gadsby, N J; Templeton, K E; McMullan, R; McKenna, J P; Rennie, J; Robb, C T; Walsh, T S; Rossi, A G; Conway Morris, A; Simpson, A J

    2016-01-01

    Background Ventilator-acquired pneumonia (VAP) remains a significant problem within intensive care units (ICUs). There is a growing recognition of the impact of critical-illness-induced immunoparesis on the pathogenesis of VAP, but the mechanisms remain incompletely understood. We hypothesised that, because of limitations in their routine detection, Mycoplasmataceae are more prevalent among patients with VAP than previously recognised, and that these organisms potentially impair immune cell function. Methods and setting 159 patients were recruited from 12 UK ICUs. All patients had suspected VAP and underwent bronchoscopy and bronchoalveolar lavage (BAL). VAP was defined as growth of organisms at >104 colony forming units per ml of BAL fluid on conventional culture. Samples were tested for Mycoplasmataceae (Mycoplasma and Ureaplasma spp.) by PCR, and positive samples underwent sequencing for speciation. 36 healthy donors underwent BAL for comparison. Additionally, healthy donor monocytes and macrophages were exposed to Mycoplasma salivarium and their ability to respond to lipopolysaccharide and undertake phagocytosis was assessed. Results Mycoplasmataceae were found in 49% (95% CI 33% to 65%) of patients with VAP, compared with 14% (95% CI 9% to 25%) of patients without VAP. Patients with sterile BAL fluid had a similar prevalence to healthy donor BAL fluid (10% (95% CI 4% to 20%) vs 8% (95% CI 2% to 22%)). The most common organism identified was M. salivarium. Blood monocytes from healthy volunteers incubated with M. salivarium displayed an impaired TNF-α response to lipopolysaccharide (p=0.0003), as did monocyte-derived macrophages (MDMs) (p=0.024). MDM exposed to M. salivarium demonstrated impaired phagocytosis (p=0.005). Discussion and conclusions This study demonstrates a high prevalence of Mycoplasmataceae among patients with VAP, with a markedly lower prevalence among patients with suspected VAP in whom subsequent cultures refuted the diagnosis. The most

  5. Brain functional magnetic resonance imaging response to glucose and fructose infusions in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: In animals, intracerebroventricular glucose and fructose have opposing effects on appetite and weight regulation. In humans, functional brain magnetic resonance imaging (fMRI) studies during carbohydrate ingestion suggest that glucose may regulate HT signaling but are potentially confoun...

  6. Bilateral responses of prefrontal and motor cortices to repetitive transcranial magnetic stimulation as measured by functional near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Tian, Fenghua; Kozel, Frank Andrew; Dhamne, Sameer; McClintock, Shawn M.; Croarkin, Paul; Mapes, Kimberly; Husain, Mustafa M.; Liu, Hanli

    2009-02-01

    Simultaneously acquiring cortical functional Near Infrared Spectroscopy (fNIRS) during repeated Transcranial Magnetic Stimulation (rTMS) offers the possibility of directly investigating the effects of rTMS on brain regions without quantifiable behavioral changes. In this study, the left motor cortex and subsequently the left prefrontal cortex were stimulated at 1 Hz while fNIRS data was simultaneously acquired. Changes in hemodynamic signals were measured on both ipsilateral and contralateral sides. In each cortex, a significantly larger decrease in the concentration of oxygenated hemoglobin and a smaller increase in the concentration of deoxygenated hemoglobin during the stimulation periods were observed in both the motor and prefrontal cortices. The ipsilateral and contralateral changes showed high temporal consistency. Same experiment was repeated for each subject 2 or 3 days later. The hemodynamic responses associated with the stimulation showed good reproducibility in two sessions. To our knowledge, this is the first report of simultaneous fNIRS measurement of ipsilateral and contralateral changes of either the motor or prefrontal cortex during rTMS stimulation.

  7. Irregular wave functions of a hydrogen atom in a uniform magnetic field

    NASA Technical Reports Server (NTRS)

    Wintgen, D.; Hoenig, A.

    1989-01-01

    The highly excited irregular wave functions of a hydrogen atom in a uniform magnetic field are investigated analytically, with wave function scarring by periodic orbits considered quantitatively. The results obtained confirm that the contributions of closed classical orbits to the spatial wave functions vanish in the semiclassical limit. Their disappearance, however, is slow. This discussion is illustrated by numerical examples.

  8. Small-angle neutron scattering correlation functions of bulk magnetic materials

    PubMed Central

    Mettus, Denis; Michels, Andreas

    2015-01-01

    On the basis of the continuum theory of micromagnetics, the correlation function of the spin-misalignment small-angle neutron scattering cross section of bulk ferromagnets (e.g. elemental polycrystalline ferromagnets, soft and hard magnetic nanocomposites, nanoporous ferromagnets, or magnetic steels) is computed. For such materials, the spin disorder which is related to spatial variations in the saturation magnetization and magnetic anisotropy field results in strong spin-misalignment scattering dΣM/dΩ along the forward direction. When the applied magnetic field is perpendicular to the incoming neutron beam, the characteristics of dΣM/dΩ (e.g. the angular anisotropy on a two-dimensional detector or the asymptotic power-law exponent) are determined by the ratio of magnetic anisotropy field strength H p to the jump ΔM in the saturation magnetization at internal interfaces. Here, the corresponding one- and two-dimensional real-space correlations are analyzed as a function of applied magnetic field, the ratio H p/ΔM, the single-particle form factor and the particle volume fraction. Finally, the theoretical results for the correlation function are compared with experimental data on nanocrystalline cobalt and nickel. PMID:26500464

  9. Phonon and magnetic structure in δ-plutonium from density-functional theory.

    PubMed

    Söderlind, Per; Zhou, F; Landa, A; Klepeis, J E

    2015-10-30

    We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure and (ii) the disordered-local-moment method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, but the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments.

  10. Phonon and magnetic structure in δ-plutonium from density-functional theory

    PubMed Central

    Söderlind, Per; Zhou, F.; Landa, A.; Klepeis, J. E.

    2015-01-01

    We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure and (ii) the disordered-local-moment method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, but the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments. PMID:26514238

  11. Magnetic assembly of transparent and conducting graphene-based functional composites

    NASA Astrophysics Data System (ADS)

    Le Ferrand, Hortense; Bolisetty, Sreenath; Demirörs, Ahmet F.; Libanori, Rafael; Studart, André R.; Mezzenga, Raffaele

    2016-06-01

    Innovative methods producing transparent and flexible electrodes are highly sought in modern optoelectronic applications to replace metal oxides, but available solutions suffer from drawbacks such as brittleness, unaffordability and inadequate processability. Here we propose a general, simple strategy to produce hierarchical composites of functionalized graphene in polymeric matrices, exhibiting transparency and electron conductivity. These are obtained through protein-assisted functionalization of graphene with magnetic nanoparticles, followed by magnetic-directed assembly of the graphene within polymeric matrices undergoing sol-gel transitions. By applying rotating magnetic fields or magnetic moulds, both graphene orientation and distribution can be controlled within the composite. Importantly, by using magnetic virtual moulds of predefined meshes, graphene assembly is directed into double-percolating networks, reducing the percolation threshold and enabling combined optical transparency and electrical conductivity not accessible in single-network materials. The resulting composites open new possibilities on the quest of transparent electrodes for photovoltaics, organic light-emitting diodes and stretchable optoelectronic devices.

  12. Phonon and magnetic structure in δ-plutonium from density-functional theory

    SciTech Connect

    Söderlind, Per; Zhou, F.; Landa, A.; Klepeis, J. E.

    2015-10-30

    We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure and (ii) the disordered-local-moment (DLM) method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, However, the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments.

  13. Polyethylenimine functionalized magnetic nanoparticles as a potential non-viral vector for gene delivery.

    PubMed

    Zhou, Yangbo; Tang, Zhaomin; Shi, Chunli; Shi, Shuai; Qian, Zhiyong; Zhou, Shaobing

    2012-11-01

    Polyethylenimine (PEI) functionalized magnetic nanoparticles were synthesized as a potential non-viral vector for gene delivery. The nanoparticles could provide the magnetic-targeting, and the cationic polymer PEI could condense DNA and avoid in vitro barriers. The magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, dynamic light scattering measurements, transmission electron microscopy, vibrating sample magnetometer and atomic force microscopy. Agarose gel electrophoresis was used to asses DNA binding and perform a DNase I protection assay. The Alamar blue assay was used to evaluate negative effects on the metabolic activity of cells incubated with PEI modified magnetic nanoparticles and their complexes with DNA both in the presence or absence of an external magnetic field. Flow cytometry and fluorescent microscopy were also performed to investigate the transfection efficiency of the DNA-loaded magnetic nanoparticles in A549 and B16-F10 tumor cells with (+M) or without (-M) the magnetic field. The in vitro transfection efficiency of magnetic nanoparticles was improved obviously in a permanent magnetic field. Therefore, the magnetic nanoparticles show considerable potential as nanocarriers for gene delivery.

  14. Magnetic resonance imaging and electromyography as indexes of muscle function

    NASA Technical Reports Server (NTRS)

    Adams, Gregory R.; Duvoisin, Marc R.; Dudley, Gary A.

    1992-01-01

    A hypothesis is tested that exercise-induced magnetic resonance (MR) contrast shifts would relate to electromyography (EMG) amplitude if both measures reflect muscle use during exercise. Both magnetic resonance images (MRI) and EMG data were obtained for separate eccentric (ECC) and cocentric (CON) exercise of increasing intensity for seven subjects 30-32 yr old. CON and ECC actions caused increased integrated EMG (IEMG) and T2 values which were strongly related with relative resistance. The rate of increase and absolute value of both T2 and IEMG were found to be greater for CON than for ECC actions. For both actions IEMG and T2 were correlated. Data obtained suggest that surface IEMG accurately reflects the contractile behavior of muscle and exercise-induced increases in MRI T2 values reflect certain processes that scale with muscle use.

  15. Hyperpolarized Magnetic Resonance as a Sensitive Detector of Metabolic Function

    PubMed Central

    2015-01-01

    Hyperpolarized magnetic resonance allows for noninvasive measurements of biochemical reactions in vivo. Although this technique provides a unique tool for assaying enzymatic activities in intact organs, the scope of its application is still elusive for the wider scientific community. The purpose of this review is to provide key principles and parameters to guide the researcher interested in adopting this technology to address a biochemical, biomedical, or medical issue. It is presented in the form of a compendium containing the underlying essential physical concepts as well as suggestions to help assess the potential of the technique within the framework of specific research environments. Explicit examples are used to illustrate the power as well as the limitations of hyperpolarized magnetic resonance. PMID:25369537

  16. THEORETICAL ESTIMATES OF TWO-POINT SHEAR CORRELATION FUNCTIONS USING TANGLED MAGNETIC FIELDS

    SciTech Connect

    Pandey, Kanhaiya L.; Sethi, Shiv K.

    2012-03-20

    The existence of primordial magnetic fields can induce matter perturbations with additional power at small scales as compared to the usual {Lambda}CDM model. We study its implication within the context of a two-point shear correlation function from gravitational lensing. We show that a primordial magnetic field can leave its imprints on the shear correlation function at angular scales {approx}< a few arcminutes. The results are compared with CFHTLS data, which yield some of the strongest known constraints on the parameters (strength and spectral index) of the primordial magnetic field. We also discuss the possibility of detecting sub-nano Gauss fields using future missions such as SNAP.

  17. Microwave absorption in nanocomposite material of magnetically functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Labunov, V. A.; Danilyuk, A. L.; Prudnikava, A. L.; Komissarov, I.; Shulitski, B. G.; Speisser, C.; Antoni, F.; Le Normand, F.; Prischepa, S. L.

    2012-07-01

    The interaction of electromagnetic radiation in X and Ka bands with magnetic nanocomposite of disordered carbon nanotubes arrays has been investigated both experimentally and theoretically. Samples were synthesized on the quartz reactor walls by decomposition of ferrocene and xylene which provided random intercalation of iron phase nanoparticles in carbon nanotube array. The exhaustive characterization of the samples by means of the scanning electron microscopy, Raman spectroscopy, and x-ray photoemission spectroscopy was performed. It was found that the absorption of the electromagnetic wave monotonically increases with the frequency. To describe these experimental data, we extended the Bruggeman effective medium theory to a more complex case of a magnetic nanocomposite with randomly distributed spherical ferromagnetic nanoparticles in a conducting medium. The essential feature of the developed model is the consideration of the complex nature of the studied material. In particular, such important parameters as magnetic and dielectric properties of both the carbon nanotube medium and the nanoparticles, the volume concentration and the dimensions of the nanoparticles, the wave impedance of the resistive-capacitive shells of the conductive nanoparticles are explicitly taken into account in our model. Moreover, analysing the experimental results, we were able to obtain the frequency dependencies of permittivity and permeability of the studied nanocomposite.

  18. Static magnetic field influence on rat brain function detected by heart rate monitoring.

    PubMed

    Veliks, Viktors; Ceihnere, Edīte; Svikis, Igors; Aivars, Juris

    2004-04-01

    The aim of the present study was to identify the effects of a static magnetic field (SMF) on rat brain structures that control autonomic functions, specifically heart rate and heart rhythmicity. The experiments were carried out on 44 male Wistar rats under ketamine-xylazine anesthesia. SMF was induced using samarium-cobalt fused magnets (20 x 20 x 10 mm in size) placed bitemporally. Magnetic induction intensity was 100 mT on the surface of the head. Duration of magnetic field application was 15 min. An electrocardiogram was recorded from limb lead II, and both heart rate (average duration of cardiac cycles) and heart rhythmicity were analyzed before and after SMF application. SMF evoked changes in both heart rate and rhythm in 80% of the animals; the predominant effects were bradycardia and disappearance of respiratory sinus arrhythmia. However, the effectiveness of SMF in large measure depends on both functional peculiarities and functional activities of brain autonomic centers.

  19. Longitudinal wave function control in single quantum dots with an applied magnetic field

    NASA Astrophysics Data System (ADS)

    Cao, Shuo; Tang, Jing; Gao, Yunan; Sun, Yue; Qiu, Kangsheng; Zhao, Yanhui; He, Min; Shi, Jin-An; Gu, Lin; Williams, David A.; Sheng, Weidong; Jin, Kuijuan; Xu, Xiulai

    2015-01-01

    Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots.

  20. Longitudinal wave function control in single quantum dots with an applied magnetic field.

    PubMed

    Cao, Shuo; Tang, Jing; Gao, Yunan; Sun, Yue; Qiu, Kangsheng; Zhao, Yanhui; He, Min; Shi, Jin-An; Gu, Lin; Williams, David A; Sheng, Weidong; Jin, Kuijuan; Xu, Xiulai

    2015-01-27

    Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots.

  1. High-permeability functionalized silicone magnetic microspheres with low autofluorescence for biomedical applications.

    PubMed

    Evans, Benjamin A; Ronecker, Julia C; Han, David T; Glass, Daniel R; Train, Tonya L; Deatsch, Alison E

    2016-05-01

    Functionalized magnetic microspheres are widely used for cell separations, isolation of proteins and other biomolecules, in vitro diagnostics, tissue engineering, and microscale force spectroscopy. We present here the synthesis and characterization of a silicone magnetic microsphere which can be produced in diameters ranging from 0.5 to 50 μm via emulsion polymerization of a silicone ferrofluid precursor. This bottom-up approach to synthesis ensures a uniform magnetic concentration across all sizes, leading to significant advances in magnetic force generation. We demonstrate that in a size range of 5-20 μm, these spheres supply a full order of magnitude greater magnetic force than leading commercial products. In addition, the unique silicone matrix exhibits autofluorescence two orders of magnitude lower than polystyrene microspheres. Finally, we demonstrate the ability to chemically functionalize our silicone microspheres using a standard EDC reaction, and show that our folate-functionalized silicone microspheres specifically bind to targeted HeLa and Jurkat cells. These spheres show tremendous potential for replacing magnetic polystyrene spheres in applications which require either large magnetic forces or minimal autofluorescence, since they represent order-of-magnitude improvements in each. In addition, the unique silicone matrix and proven biocompatibility suggest that they may be useful for encapsulation and targeted delivery of lipophilic pharmaceuticals.

  2. Continuous protein purification using functionalized magnetic nanoparticles in aqueous micellar two-phase systems.

    PubMed

    Fischer, Ingo; Hsu, Chia-Chang; Gärtner, Markus; Müller, Christine; Overton, Tim W; Thomas, Owen R T; Franzreb, Matthias

    2013-08-30

    A novel technique for technical-scale continuous purification of proteins is presented. It is based on the combined use of functionalized magnetic nano-particles and an Aqueous Micellar Two-Phase System featuring the non-ionic surfactant, Eumulgin ES, which undergoes temperature induced phase separation at ∼25°C. In the first step, conducted below the transition temperature (i.e. 15°C), the magnetic sorbent particles are added into the single dispersed phase and bind the protein of interest. Next, on raising the temperature to 30°C the protein-laden magnetic particles partition strongly into the micelle-rich top phase of the micellar two-phase system that's formed. The magnetically susceptible top phase is then continuously separated from the micelle-poor phase in a flowthrough tailor-made magnetic extractor featuring a permanent magnet providing an upwardly acting magnetic force. This separation device was shown to be effective for continuous separation of a wide range of differently sized magnetic particle sorbents (i.e. from 2μm diameter to as small as 25nm) from a 10% (w/w) Eumulgin ES system; high separation efficiencies were recorded for the phase-forming surfactant (87 to >98%), and all magnetic sorbent particles tested (95-99.9%). Finally, protein purification by continuous magnetic extraction was demonstrated at 15L scale for the recovery of an antibody fragment, A33 Fab', from a crude extract of Escherichia coli periplasm. Nearly 70% of the A33 Fab' initially present in the extract at 15.6% of the total protein content was recovered in a 2-fold concentrated and highly purified (>98%) state. Further, the amounts of magnetic sorbent and phase-forming surfactant lost in the process were very small; thus recycling of both components into subsequent rounds of continuous magnetic extraction is highly feasible.

  3. Copper nanoparticles functionalized PE: Preparation, characterization and magnetic properties

    NASA Astrophysics Data System (ADS)

    Reznickova, A.; Orendac, M.; Kolska, Z.; Cizmar, E.; Dendisova, M.; Svorcik, V.

    2016-12-01

    We report grafting of copper nanoparticles (CuNP) on plasma activated high density polyethylene (HDPE) via dithiol interlayer pointing out to the structural and magnetic properties of those composites. The as-synthesized Cu nanoparticles have been characterized by high-resolution transmission electron microscopy (HRTEM/TEM) and UV-vis spectroscopy. Properties of pristine PE and their plasma treated counterparts were studied by different experimental techniques: X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), zeta potential, electron spin resonance (ESR) and SQUID magnetometry. From TEM and HRTEM analyses, it is found that the size of high purity Cu nanoparticles is (12.2 ± 5.2) nm. It was determined that in the CuNPs, the copper atoms are arranged mostly in the (111) and (200) planes. Absorption in UV-vis region by these nanoparticles is ranging from 570 to 670 nm. EDS revealed that after 1 h of grafting are Cu nanoparticles homogeneously distributed over the whole surface and after 24 h of grafting Cu nanoparticles tend to aggregate slightly. The combined investigation of magnetic properties using ESR spectrometry and SQUID magnetometry confirmed the presence of copper nanoparticles anchored on PE substrate and indicated ferromagnetic interactions.

  4. Fluorescent magnetic nanoparticles with specific targeting functions for combinded targeting, optical imaging and magnetic resonance imaging.

    PubMed

    Chen, Yung-Chu; Chang, Wen-Hsiang; Wang, Shian-Jy; Hsieh, Wen-Yuan

    2012-01-01

    Superparamagnetic iron oxides nanoparticles possess specific magnetic properties to be an efficient contrast agent for magnetic resonance imaging (MRI) to enhance the detection and characterization of tissue lesions within the body. To endow specific properties to nanoparticles that can target cancer cells and prevent recognition by the reticuloendothelial system (RES), the surface of the nanoparticles was modified with folic-acid-conjugated poly(ethylene glycol) (FA-PEG). In this study, we investigated the multifunctional fluorescent magnetic nanoparticles (IOPFC) that can specifically target cancer cells and be monitored by both MRI and optical imaging. IOPFC consists of an iron oxide superparamagnetic nanoparticle conjugated with a layer of PEG, which was terminal modified with either Cypher5E or folic acid molecules. The core sizes of IOPFC nanoparticles are around 10 nm, which were visualized by transmission electron microscope (TEM). The hysteresis curves, generated with superconducting quantum interference device (SQUID) magnetometer analysis, demonstrated that IOPFC nanoparticles are superparamagnetic with insignificant hysteresis. IOPFC displays higher intracellular uptake into KB and MDA-MB-231 cells due to the over-expressed folate receptor. This result is confirmed by laser confocal scanning microscopy (LCSM) and atomic flow cytometry. Both in vitro and in vivo MRI studies show better IOPFC uptake by the KB cells (folate positive) than the HT1080 cells (folate negative) and, hence, stronger T 2-weighted signals enhancement. The in vivo fluorescent image recorded at 20 min post injection show strong fluorescence from IOPFC which can be observed around the tumor region. This multifunctional nanoparticle can assess the potential application of developing a magnetic nanoparticle system that combines tumor targeting, as well as MRI and optical imaging.

  5. Spin and charge pumping in magnetic tunnel junctions with precessing magnetization: A nonequilibrium Green function approach

    NASA Astrophysics Data System (ADS)

    Chen, Son-Hsien; Chang, Ching-Ray; Xiao, John Q.; Nikolić, Branislav K.

    2009-02-01

    We study spin and charge currents pumped by precessing magnetization of a single ferromagnetic layer within F|I|N or F|I|F ( F -ferromagnet; I -insulator; N -normal metal) multilayers of nanoscale thickness attached to two normal-metal electrodes with no applied bias voltage between them. Both simple one-dimensional model, consisting of a single precessing spin and a potential barrier as the “sample,” and realistic three-dimensional devices are investigated. In the rotating reference frame, where the magnetization appears to be static, these junctions are mapped onto a four-terminal dc circuit whose effectively half-metallic ferromagnetic electrodes are biased by the frequency ℏω/e of microwave radiation driving magnetization precession at the ferromagnetic resonance (FMR) conditions. We show that pumped spin current in F|I|F junctions, diminished behind the tunnel barrier and increased in the opposite direction, is filtered into charge current by the second F layer to generate dc pumping voltage of the order of ˜1μV (at FMR frequency ˜10GHz ) in an open circuit. In F|I|N devices, several orders of magnitude smaller charge current and the corresponding dc voltage appear concomitantly with the pumped spin current due to barrier induced asymmetry in the transmission coefficients connecting the four electrodes in the rotating-frame picture of pumping.

  6. Multi-functional Magnetic Nanoparticles for Magnetic Resonance Imaging and Cancer Therapy

    PubMed Central

    Yallapu, Murali M.; Othman, Shadi F.; Curtis, Evan T.; Gupta, Brij K.; Jaggi, Meena; Chauhan, Subhash C.

    2010-01-01

    We have developed a multi-layer approach for the synthesis of water-dispersible superparamagnetic iron oxide nanoparticles for hyperthermia, magnetic resonance imaging (MRI) and drug delivery applications. In this approach, iron oxide core nanoparticles were obtained by precipitation of iron salts in the presence of ammonia and provided β-cyclodextrin and pluronic polymer (F127) coatings. This formulation (F127250) was highly water dispersible which allowed encapsulation of the anti-cancer drug(s) in β-cyclodextrin and pluronic polymer for sustained drug release. The F127250 formulation has exhibited superior hyperthermia effects over time under alternating magnetic field compared to pure magnetic nanoparticles (MNP) and β-cyclodextrin coated nanoparticles (CD200). Additionally, the improved MRI characteristics were also observed for the F127250 formulation in agar gel and in cisplatin resistant ovarian cancer cells (A12780CP) compared to MNP and CD200 formulations. Furthermore, the drug loaded formulation of F127250 exhibited many folds of imaging contrast properties. Due to the internalization capacity of the F127250 formulation, its curcumin loaded formulation (F127250-CUR) exhibited almost equivalent inhibition effects on A2780CP (ovarian), MDA-MB-231 (breast), and PC3 (prostate) cancer cells even though curcumin release was only 40%. The improved therapeutic effects were verified by examining molecular effects using Western blotting and transmission electron microscopic (TEM) studies. F127250-CUR also exhibited haemocompatibility, suggesting a nanochemo-therapuetic agent for cancer therapy. PMID:21167595

  7. Multi-functional magnetic nanoparticles for magnetic resonance imaging and cancer therapy.

    PubMed

    Yallapu, Murali M; Othman, Shadi F; Curtis, Evan T; Gupta, Brij K; Jaggi, Meena; Chauhan, Subhash C

    2011-03-01

    We have developed a multi-layer approach for the synthesis of water-dispersible superparamagnetic iron oxide nanoparticles for hyperthermia, magnetic resonance imaging (MRI) and drug delivery applications. In this approach, iron oxide core nanoparticles were obtained by precipitation of iron salts in the presence of ammonia and provided β-cyclodextrin and pluronic polymer (F127) coatings. This formulation (F127250) was highly water dispersible which allowed encapsulation of the anti-cancer drug(s) in β-cyclodextrin and pluronic polymer for sustained drug release. The F127250 formulation has exhibited superior hyperthermia effects over time under alternating magnetic field compared to pure magnetic nanoparticles (MNP) and β-cyclodextrin coated nanoparticles (CD200). Additionally, the improved MRI characteristics were also observed for the F127250 formulation in agar gel and in cisplatin resistant ovarian cancer cells (A12780CP) compared to MNP and CD200 formulations. Furthermore, the drug-loaded formulation of F127250 exhibited many folds of imaging contrast properties. Due to the internalization capacity of the F127250 formulation, its curcumin-loaded formulation (F127250-CUR) exhibited almost equivalent inhibition effects on A2780CP (ovarian), MDA-MB-231 (breast), and PC-3 (prostate) cancer cells even though curcumin release was only 40%. The improved therapeutic effects were verified by examining molecular effects using Western blotting and transmission electron microscopic (TEM) studies. F127250-CUR also exhibited haemocompatibility, suggesting a nanochemo-therapeutic agent for cancer therapy.

  8. Evaluating Swallowing Muscles Essential for Hyolaryngeal Elevation by Using Muscle Functional Magnetic Resonance Imaging

    SciTech Connect

    Pearson, William G.; Hindson, David F.; Langmore, Susan E.; Zumwalt, Ann C.

    2013-03-01

    Purpose: Reduced hyolaryngeal elevation, a critical event in swallowing, is associated with radiation therapy. Two muscle groups that suspend the hyoid, larynx, and pharynx have been proposed to elevate the hyolaryngeal complex: the suprahyoid and longitudinal pharyngeal muscles. Thought to assist both groups is the thyrohyoid, a muscle intrinsic to the hyolaryngeal complex. Intensity modulated radiation therapy guidelines designed to preserve structures important to swallowing currently exclude the suprahyoid and thyrohyoid muscles. This study used muscle functional magnetic resonance imaging (mfMRI) in normal healthy adults to determine whether both muscle groups are active in swallowing and to test therapeutic exercises thought to be specific to hyolaryngeal elevation. Methods and Materials: mfMRI data were acquired from 11 healthy subjects before and after normal swallowing and after swallowing exercise regimens (the Mendelsohn maneuver and effortful pitch glide). Whole-muscle transverse relaxation time (T2 signal, measured in milliseconds) profiles of 7 test muscles were used to evaluate the physiologic response of each muscle to each condition. Changes in effect size (using the Cohen d measure) of whole-muscle T2 profiles were used to determine which muscles underlie swallowing and swallowing exercises. Results: Post-swallowing effect size changes (where a d value of >0.20 indicates significant activity during swallowing) for the T2 signal profile of the thyrohyoid was a d value of 0.09; a d value of 0.40 for the mylohyoid, 0.80 for the geniohyoid, 0.04 for the anterior digastric, and 0.25 for the posterior digastric-stylohyoid in the suprahyoid muscle group; and d values of 0.47 for the palatopharyngeus and 0.28 for the stylopharyngeus muscles in the longitudinal pharyngeal muscle group. The Mendelsohn maneuver and effortful pitch glide swallowing exercises showed significant effect size changes for all muscles tested, except for the thyrohyoid. Conclusions

  9. Brain Activation during Semantic Processing in Autism Spectrum Disorders via Functional Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Harris, Gordon J.; Chabris, Christopher F.; Clark, Jill; Urban, Trinity; Aharon, Itzhak; Steele, Shelley; McGrath, Lauren; Condouris, Karen; Tager-Flusberg, Helen

    2006-01-01

    Language and communication deficits are core features of autism spectrum disorders (ASD), even in high-functioning adults with ASD. This study investigated brain activation patterns using functional magnetic resonance imaging in right-handed adult males with ASD and a control group, matched on age, handedness, and verbal IQ. Semantic processing in…

  10. [Functional magnetic resonance imaging: physiopathology, techniques and applications].

    PubMed

    Delmaire, C; Krainik, A; Lethuc, V; Reyns, N; Duffau, H; Capelle, L; Lehéricy, S

    2007-03-01

    Brain functional MRI (fMRI) provides an indirect mapping of cerebral activity, based on the detection of local changes in blood flow and oxygenation levels that are associated with neuronal activity (BOLD contrast). fMRI allows noninvasive studies of normal and pathological aspects of the brain's functional organization. It is based on the comparison of two or more cognitive states. Echoplanar imaging is the technique of choice, providing the quickest study of the entire brain. Activation maps are calculated from a statistical analysis of the local signal changes. fMRI has become one of the most widely used functional imaging techniques in neuroscience. In clinical practice, fMRI can identify eloquent areas involved in motor and language functions in surgical patients and can evaluate the risk of postoperative neurological deficit.

  11. Modelling and analysis of magnetic memory testing method based on the density functional theory

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Fu, Ying; Jian, Ren

    2015-01-01

    Metal magnetic memory (MMM) method is a novel, passive magnetic method for inspecting mechanical degradation of ferromagnetic components. To promote a further understanding of the MMM testing mechanism, the relationship between stress concentration and the self-magnetic leakage field measured by MMM effect was quantitatively interpreted using a density functional theory based on the generalised gradient approximation. Meanwhile, the influence of doping effect on MMM signal was calculated. Interestingly, the theoretical approach is in very good agreement with the experimental observations. A new research programme for quantitative interpretation of the MMM effect was initiated.

  12. Combined Effects of Acrobatic Exercise and Magnetic Stimulation on the Functional Recovery after Spinal Cord Lesions

    PubMed Central

    Wieraszko, Andrzej

    2008-01-01

    Abstract The objective of the study was to determine whether physical exercise combined with epidural spinal cord magnetic stimulation could improve recovery after injury of the spinal cord. Spinal cord lesioning in mice resulted in reduced locomotor function and negatively affected the muscle strength tested in vitro. Acrobatic exercise attenuated the behavioral effects of spinal cord injury. The exposure to magnetic fields facilitated further this improvement. The progress in behavioral recovery was correlated with reduced muscle degeneration and enhanced muscle contraction. The acrobatic exercise combined with stimulation with magnetic fields significantly facilitates behavioral recovery and muscle physiology in mice following spinal cord injury. PMID:18986227

  13. Nanometric resolution magnetic resonance imaging methods for mapping functional activity in neuronal networks.

    PubMed

    Boretti, Albert; Castelletto, Stefania

    2016-01-01

    This contribution highlights and compares some recent achievements in the use of k-space and real space imaging (scanning probe and wide-filed microscope techniques), when applied to a luminescent color center in diamond, known as nitrogen vacancy (NV) center. These techniques combined with the optically detected magnetic resonance of NV, provide a unique platform to achieve nanometric magnetic resonance imaging (MRI) resolution of nearby nuclear spins (known as nanoMRI), and nanometric NV real space localization. •Atomic size optically detectable spin probe.•High magnetic field sensitivity and nanometric resolution.•Non-invasive mapping of functional activity in neuronal networks.

  14. A probabilistic functional atlas of the VIM nucleus constructed from pre-, intra- and postoperative electrophysiological and neuroimaging data acquired during the surgical treatment of Parkinson's disease patients.

    PubMed

    Nowinski, Wieslaw L; Belov, Dmitry; Thirunavuukarasuu, A; Benabid, Alim Louis

    2005-01-01

    We have previously introduced a concept of a probabilistic functional atlas (PFA) to overcome limitations of the current electronic stereotactic brain atlases: anatomical nature, spatial sparseness, inconsistency and lack of population information. The PFA for the STN has already been developed. This work addresses construction of the PFA for the ventrointermediate nucleus (PFA-VIM). The PFA-VIM is constructed from pre-, intra- and postoperative electrophysiological and neuroimaging data acquired during the surgical treatment of Parkinson's disease patients. The data contain the positions of the chronically implanted electrodes and their best contacts. For each patient, the intercommissural distance, height of the thalamus and width of the third ventricle were measured. An algorithm was developed to convert these data into the PFA-VIM, and to present them on axial, coronal and sagittal planes and in 3-D. The PFA-VIM gives a spatial distribution of the best contacts, and its probability is proportional to best contact concentration in a given location. The region with the highest probability corresponds to the best target. The PFA-VIM is calculated with 0.25-mm3 resolution from 107 best contacts in two situations: with and without lateral compensation against the width of the third ventricle. For the PFA-VIM compensated laterally, the anterior, lateral and dorsal coordinates of the mean value are (in mm) 6.24, 13.83, 1.68 for the left VIM and 6.54, -13.84, 2.10 for the right VIM. The coordinates of the mean value of the highest probability region along with the highest number of the best contacts (P) are: 6.25, 14.25, 1.75, P = 16, for the left VIM, and 6.0, -14.0, 1.00, P = 18, for the right VIM. The coordinate system origin is at the posterior commissure. For the PFA-VIM not compensated laterally, the coordinates of the mean value are 6.24, 13.99, 1.68 for the left VIM and 6.53, -14.13, 2.10 for the right VIM. The coordinates of the mean value of the highest

  15. Acquired Idiopathic Generalized Anhidrosis.

    PubMed

    Gangadharan, Geethu; Criton, Sebastian; Surendran, Divya

    2015-01-01

    Acquired idiopathic generalized anhidrosis is a rare condition, where the exact pathomechanism is unknown. We report a case of acquired idiopathic generalized anhidrosis in a patient who later developed lichen planus. Here an autoimmune-mediated destruction of sweat glands may be the probable pathomechanism.

  16. LABORATORY-ACQUIRED MYCOSES

    DTIC Science & Technology

    laboratory- acquired mycoses . Insofar as possible, the etiological fungus, type of laboratory, classification of personnel, type of work conducted, and other...pertinent data have been listed in this study. More than 288 laboratory- acquired mycoses are described here, including 108 cases of

  17. Long-Circulating Heparin-Functionalized Magnetic Nanoparticles for Potential Application as a Protein Drug Delivery Platform

    PubMed Central

    Zhang, Jian; Shin, Meong Cheol; David, Allan E.; Zhou, Jie; Lee, Kyuri; He, Huining; Yang, Victor C.

    2013-01-01

    Starch-coated, PEGylated and heparin-functionalized iron oxide magnetic nanoparticles (DNPH) were successfully synthesized and characterized in detail. The PEGylation (20 kDa) process resulted in an average coating of 430 PEG molecules per nanoparticle. After that, heparin conjugation was carried out to attain the final DNPH platform with 35.4 μg of heparin/mg Fe. Commercially acquired heparin-coated magnetic nanoparticles were also PEGylated (HP) and characterized for comparison. Protamine was selected as a model protein to demonstrate the strong binding affinity and high loading content of DNPH for therapeutically relevant cationic proteins. DNPH showed a maximum loading of 22.9 μg protamine/mg Fe. In the pharmacokinetic study, DNPH displayed a long-circulating half-life of 9.37 h, 37.5-fold longer than that (0.15 h) of H P. This improved plasma stability enabled extended exposure of DNPH to the tumor lesions, as was visually confirmed in a flank 9L-glioma mouse model using magnetic resonance imaging (MRI). Quantitative analysis of the Fe content in excised tumor lesions further demonstrated the superior tumor targeting ability of DNPH, with up to 31.36 μg Fe/g tissue (13.07% injected dose (I.D.)/g tissue) and 7.5-fold improvement over that (4.27 μg Fe/g tissue; 1.78% I.D./g tissue) of HP. Overall, DNPH shed light of the potential to be used as a protein drug delivery platform. PMID:24024964

  18. Tailored functionalization of iron oxide nanoparticles for MRI, drug delivery, magnetic separation and immobilization of biosubstances.

    PubMed

    Hola, Katerina; Markova, Zdenka; Zoppellaro, Giorgio; Tucek, Jiri; Zboril, Radek

    2015-11-01

    In this critical review, we outline various covalent and non-covalent approaches for the functionalization of iron oxide nanoparticles (IONPs). Tuning the surface chemistry and design of magnetic nanoparticles are described in relation to their applicability in advanced medical technologies and biotechnologies including magnetic resonance imaging (MRI) contrast agents, targeted drug delivery, magnetic separations and immobilizations of proteins, enzymes, antibodies, targeting agents and other biosubstances. We review synthetic strategies for the controlled preparation of IONPs modified with frequently used functional groups including amine, carboxyl and hydroxyl groups as well as the preparation of IONPs functionalized with other species, e.g., epoxy, thiol, alkane, azide, and alkyne groups. Three main coupling strategies for linking IONPs with active agents are presented: (i) chemical modification of amine groups on the surface of IONPs, (ii) chemical modification of bioactive substances (e.g. with fluorescent dyes), and (iii) the activation of carboxyl groups mainly for enzyme immobilization. Applications for drug delivery using click chemistry linking or biodegradable bonds are compared to non-covalent methods based on polymer modified condensed magnetic nanoclusters. Among many challenges, we highlight the specific surface engineering allowing both therapeutic and diagnostic applications (theranostics) of IONPs and magnetic/metallic hybrid nanostructures possessing a huge potential in biocatalysis, green chemistry, magnetic bioseparations and bioimaging.

  19. Electron Velocity Distribution Function in Magnetic Clouds in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Nieves-Chinchil, Teresa; Vinas, Adolfo F.; Bale, Stuart D.

    2006-01-01

    We present a study of the kinetic properties of the electron velocity distribution functions within magnetic clouds, since they are the dominant thermal component. The study is based on high time resolution data from the GSFC WIND/SWE electron spectrometer and the Berkeley 3DP electron plasma instruments. Recent studies on magnetic clouds have shown observational evidence of anti-correlation between the total electron density and electron temperature, which suggest a polytrope law P(sub e) = alpha(Nu(sub e) (sup gamma)) for electrons with the constant gamma approximates 0.5 < 1. This anti-correlation and small polytropic gamma-values is interpreted in the context of the presence of highly non-Maxwellian electron distributions (i.e. non-thermal) within magnetic clouds. These works suggested that the non-thermal electrons can contribute as much as 50% of the total electron pressure within magnetic clouds. We have revisited some of the magnetic cloud events previously studied and attempted to quantify the nature of the non-thermal electrons by modeling the electron velocity distribution function using a kappa distribution function to characterize the kinetic non-thermal effects. If non-thermal tail effects are the source for the anti-correlation between the moment electron temperature and density and if the kappa distribution is a reasonable representative model of non-thermal effects, then the electron velocity distribution within magnetic clouds should show indication for small K-values when gamma < 1.

  20. Advances in functional magnetic resonance imaging: technology and clinical applications.

    PubMed

    Dickerson, Bradford C

    2007-07-01

    Functional MRI (fMRI) is a valuable method for use by clinical investigators to study task-related brain activation in patients with neurological or neuropsychiatric illness. Despite the relative infancy of the field, the rapid adoption of this functional neuroimaging technology has resulted from, among other factors, its ready availability, its relatively high spatial and temporal resolution, and its safety as a noninvasive imaging tool that enables multiple repeated scans over the course of a longitudinal study, and thus may lend itself well as a measure in clinical drug trials. Investigators have used fMRI to identify abnormal functional brain activity during task performance in a variety of patient populations, including those with neurodegenerative, demyelinating, cerebrovascular, and other neurological disorders that highlight the potential utility of fMRI in both basic and clinical spheres of research. In addition, fMRI studies reveal processes related to neuroplasticity, including compensatory hyperactivation, which may be a universally-occurring, adaptive neural response to insult. Functional MRI is being used to study the modulatory effects of genetic risk factors for neurological disease on brain activation; it is being applied to differential diagnosis, as a predictive biomarker of disease course, and as a means to identify neural correlates of neurotherapeutic interventions. Technological advances are rapidly occurring that should provide new applications for fMRI, including improved spatial resolution, which promises to reveal novel insights into the function of fine-scale neural circuitry of the human brain in health and disease.

  1. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: A Green's function model for ferromagnetism and spin excitations of (Ga, Mn)As diluted magnetic semiconductors

    NASA Astrophysics Data System (ADS)

    Liu, Gui-Bin; Liu, Bang-Gui

    2009-11-01

    We study (Ga, Mn)As diluted magnetic semiconductors in terms of the Ruderman-Kittel-Kasuya-Yosida quantum spin model in Green's function approach. Random distributions of the magnetic atoms are treated by using an analytical average of magnetic configurations. Average magnetic moments and spin excitation spectra as functions of temperature can be obtained by solving self-consistent equations, and the Curie temperature TC is given explicitly. TC is proportional to magnetic atomic concentration, and there exists a maximum for TC as a function of carrier concentration. Applied to (Ga, Mn)As, the theoretical results are consistent with experiment and the experimental TC can be obtained with reasonable parameters. This modelling can also be applied to other diluted magnetic semiconductors.

  2. ``Green'' functionalization of magnetic nanoparticles via tea polyphenol for magnetic resonance/fluorescent dual-imaging

    NASA Astrophysics Data System (ADS)

    Jiang, Wen; Lai, Kuilin; Liu, Kexia; Xia, Rui; Gao, Fabao; Wu, Yao; Gu, Zhongwei

    2014-01-01

    Tea polyphenol serves as an environmentally friendly ligand-exchange molecule to synthesize multifunctional metal-doped superparamagnetic iron oxide nanoparticles via a catechol-metal coordination interaction. The resultant particles not only exhibit excellent hydrophilicity and protein adsorption resistance, but also are applicable as magnetic resonance/fluorescent dual-imaging probes due to their high T2 relaxivity, autofluorescence and large cellular uptake.Tea polyphenol serves as an environmentally friendly ligand-exchange molecule to synthesize multifunctional metal-doped superparamagnetic iron oxide nanoparticles via a catechol-metal coordination interaction. The resultant particles not only exhibit excellent hydrophilicity and protein adsorption resistance, but also are applicable as magnetic resonance/fluorescent dual-imaging probes due to their high T2 relaxivity, autofluorescence and large cellular uptake. Electronic supplementary information (ESI) available: Additional information and figures (Fig. S1-S7), including experimental sections, characterization of the products, protein corona analysis, cytotoxicity and cellular uptake quantification. See DOI: 10.1039/c3nr05003c

  3. A comprehensive neuropsychological mapping battery for functional magnetic resonance imaging.

    PubMed

    Karakas, Sirel; Baran, Zeynel; Ceylan, Arzu Ozkan; Tileylioglu, Emre; Tali, Turgut; Karakas, Hakki Muammer

    2013-11-01

    Existing batteries for FMRI do not precisely meet the criteria for comprehensive mapping of cognitive functions within minimum data acquisition times using standard scanners and head coils. The goal was to develop a battery of neuropsychological paradigms for FMRI that can also be used in other brain imaging techniques and behavioural research. Participants were 61 healthy, young adult volunteers (48 females and 13 males, mean age: 22.25 ± 3.39 years) from the university community. The battery included 8 paradigms for basic (visual, auditory, sensory-motor, emotional arousal) and complex (language, working memory, inhibition/interference control, learning) cognitive functions. Imaging was performed using standard functional imaging capabilities (1.5-T MR scanner, standard head coil). Structural and functional data series were analysed using Brain Voyager QX2.9 and Statistical Parametric Mapping-8. For basic processes, activation centres for individuals were within a distance of 3-11 mm of the group centres of the target regions and for complex cognitive processes, between 7 mm and 15 mm. Based on fixed-effect and random-effects analyses, the distance between the activation centres was 0-4 mm. There was spatial variability between individual cases; however, as shown by the distances between the centres found with fixed-effect and random-effects analyses, the coordinates for individual cases can be used to represent those of the group. The findings show that the neuropsychological brain mapping battery described here can be used in basic science studies that investigate the relationship of the brain to the mind and also as functional localiser in clinical studies for diagnosis, follow-up and pre-surgical mapping.

  4. Functional magnetic resonance imaging of chronic dysarthric speech after childhood brain injury: reliance on a left-hemisphere compensatory network.

    PubMed

    Morgan, Angela T; Masterton, Richard; Pigdon, Lauren; Connelly, Alan; Liégeois, Frédérique J

    2013-02-01

    Severe and persistent speech disorder, dysarthria, may be present for life after brain injury in childhood, yet the neural correlates of this chronic disorder remain elusive. Although abundant literature is available on language reorganization after lesions in childhood, little is known about the capacity of motor speech networks to reorganize after injury. Here, we examine the structural and functional neural correlates associated with chronic dysarthria after childhood-onset traumatic brain injury. Forty-nine participants aged 12 years 3 months to 24 years 11 months were recruited to the study: (i) a group with chronic dysarthria (n = 17); matched for age and sex with two control groups of (ii) healthy control subjects (n = 17); and (iii) individuals without dysarthria after traumatic brain injury (n = 15). A high-resolution 3D T(1)-weighted whole-brain data set was acquired for voxel-based morphometry analyses of group differences in grey matter. Functional magnetic resonance imaging was used to localize activation associated with speaking single words (baseline: listening to words). Group differences on voxel-based morphometry revealed widespread grey matter reductions in the dysarthric group compared with healthy control subjects, including in numerous speech motor regions bilaterally, such as the cerebellum, the basal ganglia and primary motor cortex representation of the articulators. Relative to the non-dysarthric traumatic brain injury group, individuals with dysarthria showed reduced grey matter bilaterally in the ventral sensorimotor cortex, but this reduction was concomitant with increased functional activation only in the left-hemisphere cluster during speech. Finally, increased recruitment of Broca's area (Brodmann area 45, pars triangularis) but not its right homologue, correlated with better speech outcome, suggesting that this 'higher-level' area may be more critically involved with production when associated motor speech regions are damaged. We

  5. Structural and magnetic properties of turmeric functionalized CoFe2O4 nanocomposite powder

    NASA Astrophysics Data System (ADS)

    Mehran, E.; Farjami Shayesteh, S.; Sheykhan, M.

    2016-10-01

    The structural and magnetic properties of the synthesized pure and functionalized CoFe2O4 magnetic nanoparticles (NPs) are studied by analyzing the results from the x-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR spectroscopy, thermogravimetry (TG), and vibrating sample magnetometer (VSM). To extract the structure and lattice parameters from the XRD analysis results, we first apply the pseudo-Voigt model function to the experimental data obtained from XRD analysis and then the Rietveld algorithm is used in order to optimize the model function to estimate the true intensity values. Our simulated intensities are in good agreement with the experimental peaks, therefore, all structural parameters such as crystallite size and lattice constant are achieved through this simulation. Magnetic analysis reveals that the synthesized functionalized NPs have a saturation magnetization almost equal to that of pure nanoparticles (PNPs). It is also found that the presence of the turmeric causes a small reduction in coercivity of the functionalized NPs in comparison with PNP. Our TGA and FTIR results show that the turmeric is bonded very well to the surface of the NPs. So it can be inferred that a nancomposite (NC) powder of turmeric and nanoparticles is produced. As an application, the anti-arsenic characteristic of turmeric makes the synthesized functionalized NPs or NC powder a good candidate for arsenic removal from polluted industrial waste water. Project supported by the University of Guilan and the Iran Nanotechnology Initiative Council.

  6. Functional Magnetic Resonance Imaging in Abstinent MDMA Users: A Review.

    PubMed

    Garg, Aayushi; Kapoor, Saloni; Goel, Mishita; Chopra, Saurav; Chopra, Manav; Kapoor, Anirudh; McCann, Una D; Behera, Chittaranjan

    2015-01-01

    Ecstasy or 3,4-methylenedioxymethamphetamine (MDMA) is a popular drug of abuse. In the animal studies MDMA has been shown to have deleterious effects on the serotonergic neurotransmitter system. Understanding the adverse effects of MDMA on human brain function is of considerable importance owing to the rising number of MDMA users. Various neuroimaging studies have investigated the structural, chemical and functional differences in the brain integrity of chronic MDMA users. Various neurocognitive domains like working memory, episodic memory, semantic memory, visual stimulation, motor function and impulsivity have been compared between chronic MDMA users and nonusers using fMRI. The fMRI studies remain much more sensitive in studying the neurological deficits associated with chronic MDMA use as compared to the cognitive studies alone and therefore they serve as a prelude in our understanding of MDMA induced neurotoxicity. However they still face certain limitations contributing to inconsistency in the results and further research is needed before we can draw definitive conclusions regarding the neurotoxic effects of MDMA.

  7. Acquired inflammatory demyelinating neuropathies.

    PubMed

    Ensrud, E R; Krivickas, L S

    2001-05-01

    The acquired demyelinating neuropathies can be divided into those with an acute onset and course and those with a more chronic course. The acute neuropathies present as Guillain-Barré syndrome and include acute inflammatory demyelinating polyradiculoneuropathy (AIDP), Miller Fisher syndrome, acute motor axonal neuropathy (AMAN), acute motor and sensory axonal neuropathy (AMSAN), and acute pandysautonomia. The chronic neuropathies are collectively known as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and include MADSAM (multifocal acquired demyelinating sensory and motor neuropathy, also know as Lewis-Sumner syndrome) and DADS (distal acquired demyelinating symmetric neuropathy) as variants. The clinical features, pathology, pathogenesis, diagnosis, treatment, rehabilitation, and prognosis of these neuropathies are discussed.

  8. Study of magnetism in nano structures of graphene and functionalized graphene: a first principle study

    NASA Astrophysics Data System (ADS)

    Kumar, N.; Sharma, M.; Sharma, J. D.; Ahluwalia, P. K.

    2015-02-01

    A first principle calculation has been performed to explore the magnetism in nano structures of graphene due to vacancies in carbon lattice and functionalized (hydrogenated) graphene due to vacancies in hydrogen lattice. Nano structures containing 50C atoms (5 × 5 × 1 super cell) have been considered. Using the method of numeric localized atomic orbitals, pseudo potentials and density functional theory, spin polarised electron density of states have been calculated and C-C bond lengths, C-C-C and H-C-C bond angles, formation energy and magnetic moment have been obtained. It has been found that due to defects (vacancies) in carbon lattice of pristine graphene, nano structure develops magnetic moment, which varies with the size of defect. A nano structure with four contiguous vacancies is found to have a magnetic moment of 2.0 µB. The nano structures of hydrogenated graphene also develop magnetic moment due to vacancies in hydrogen lattice , which varies with number and position of vacancies. A nano structure with half hydrogenated graphene obtained by removing all the hydrogen atoms from one side of graphane, (alternate vacancies in hydrogen lattice 50C25H atoms, graphone) is found to develop a large magnetic moment of 25.0 µB.

  9. Surface functionalization for tailoring the aggregation and magnetic behaviour of silica-coated iron oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Roca, A. G.; Carmona, D.; Miguel-Sancho, N.; Bomatí-Miguel, O.; Balas, F.; Piquer, C.; Santamaría, J.

    2012-04-01

    We report here a detailed structural and magnetic study of different silica nanocapsules containing uniform and highly crystalline maghemite nanoparticles. The magnetic phase consists of 5 nm triethylene glycol (TREG)- or dimercaptosuccinic acid (DMSA)-coated maghemite particles. TREG-coated nanoparticles were synthesized by thermal decomposition. In a second step, TREG ligands were exchanged by DMSA. After the ligand exchange, the ζ potential of the particles changed from - 10 to - 40 mV, whereas the hydrodynamic size remained constant at around 15 nm. Particles coated by TREG and DMSA were encapsulated in silica following a sol-gel procedure. The encapsulation of TREG-coated nanoparticles led to large magnetic aggregates, which were embedded in coalesced silica structures. However, DMSA-coated nanoparticles led to small magnetic clusters inserted in silica spheres of around 100 nm. The final nanostructures can be described as the result of several competing factors at play. Magnetic measurements indicate that in the TREG-coated nanoparticles the interparticle magnetic interaction scenario has not dramatically changed after the silica encapsulation, whereas in the DMSA-coated nanoparticles, the magnetic interactions were screened due to the function of the silica template. Moreover, the analysis of the AC susceptibility suggests that our systems essentially behave as cluster spin glass systems.

  10. A comparison of spectral quality in magnetic resonance spectroscopy data acquired with and without a novel EPI-navigated PRESS sequence in school-aged children with fetal alcohol spectrum disorders.

    PubMed

    Hess, Aaron T; Jacobson, Sandra W; Jacobson, Joseph L; Molteno, Christopher D; van der Kouwe, André J W; Meintjes, Ernesta M

    2014-06-01

    Single voxel spectroscopy (SVS) can generate useful information regarding metabolite concentrations provided that the MR signal can be averaged over several minutes during which the subject remains stationary. This requirement can be particularly challenging for children who cannot otherwise be scanned without sedation. To address this problem we developed an EPI volume navigated (vNav) SVS PRESS sequence, which applies real-time head pose (location and orientation), frequency, and first-order B0 shim adjustments. A water-independent preprocessing algorithm removes residual frequency and phase shifts resulting from within-TR movements. We compare results and performance of the standard and vNav PRESS sequences in a sample of 9- to 10-year-olds from a South African cohort of children with fetal alcohol spectrum disorders (FASD) and healthy controls. Magnetic resonance spectroscopy (MRS) data in the deep cerebellar nuclei were initially acquired with the standard PRESS sequence. The children were re-scanned 1 year later with the vNav PRESS sequence. Good quality data were acquired in 73% using the vNav PRESS sequence, compared to only 50% for the standard PRESS sequence. Additionally, tighter linewidths and smaller variances in the measured concentrations were observed. These findings confirm previous reports demonstrating the efficacy of our innovative vNav sequence with healthy volunteers and young children with HIV and expand its application to a school-aged population with FASD-disorders often associated with attention problems and hyperactivity. This study provides the most direct evidence to date regarding degree to which these new methods can improve data quality in research studies employing MRS.

  11. Fluorescent chitosan functionalized magnetic polymeric nanoparticles: Cytotoxicity and in vitro evaluation of cellular uptake.

    PubMed

    Kaewsaneha, Chariya; Jangpatarapongsa, Kulachart; Tangchaikeeree, Tienrat; Polpanich, Duangporn; Tangboriboonrat, Pramuan

    2014-11-01

    Nanoparticles possessing magnetic and fluorescent properties were fabricated by the covalent attachment of fluorescein isothiocyanate onto magnetic polymeric nanoparticles functionalized by chitosan. The synthesized magnetic polymeric nanoparticles-chitosan/fluorescein isothiocyanate were successfully used for labeling the living organ and blood-related cancer cells, i.e., HeLa, Hep G2, and K562 cells. The cytotoxicity test of nanoparticles at various incubation times indicated the high cell viability (>90%) without morphological change. The confocal microscopy revealed that they could pass through cell membrane within 2 h for K562 cells and 3 h for HeLa and Hep G2 cells and then confine inside cytoplasm of all types of tested cells for at least 24 h. Therefore, the synthesized magnetic polymeric nanoparticles-chitosan/fluorescein isothiocyanate would potentially be used as cell tracking in theranostic applications.

  12. Mass spectrum and correlation functions of non-Abelian quantum magnetic monopoles

    NASA Astrophysics Data System (ADS)

    Marino, E. C.; Ramos, Rudnei O.

    1994-01-01

    The method of quantization of magnetic monopoles based on the order-disorder duality existing between the monopole operator and the Lagrangian fields is applied to the description of the quantum magnetic monopoles of 't Hooft and Polyakov in the SO(3) Georgi-Glashow model. The commutator of the monopole operator with the magnetic charge is computed explicitly, indicating that indeed the quantum monopole carries 4π/g units of magnetic charge. An explicit expression for the asymptotic behavior of the monopole correlation function is derived. From this, the mass of the quantum monopole is obtained. The tree-level result for the quantum monopole mass is shown to satisfy the Bogomol'nyi bound (Mmon>=4πM/g2) and to be within the range of values found for the energy of the classical monopole solution.

  13. Stability of a pinned magnetic domain wall as a function of its internal configuration

    SciTech Connect

    Montaigne, F.; Duluard, A.; Briones, J.; Lacour, D.; Hehn, M.; Childress, J. R.

    2015-01-14

    It is shown that there are many stable configurations for a domain wall pinned by a notch along a magnetic stripe. The stability of several of these configurations is investigated numerically as a function of the thickness of the magnetic film. The depinning mechanism depends on the structure of the domain wall and on the thickness of the magnetic film. In the case of a spin-valve structure, it appears that the stray fields emerging from the hard layer at the notch location influence the stability of the micromagnetic configuration. Different depinning mechanisms are thus observed for the same film thickness depending on the magnetization orientation of the propagating domain. This conclusion qualitatively explains experimental magnetoresistance measurements.

  14. Acquired color vision deficiency.

    PubMed

    Simunovic, Matthew P

    2016-01-01

    Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

  15. Reliability of range-separated hybrid functionals for describing magnetic coupling in molecular systems

    NASA Astrophysics Data System (ADS)

    Rivero, Pablo; Moreira, Ibério de P. R.; Illas, Francesc; Scuseria, Gustavo E.

    2008-11-01

    The performance of the Heyd-Scuseria-Ernzerhorf (HSE) and single parameter long-range corrected Perdew-Burke-Ernzerhorf (LC-ωPBE) range-separated hybrids for predicting magnetic coupling constants has been investigated for a broad set of magnetic molecular systems for which accurate experimental data exist. The set includes the H-He-H model system, two organic diradicals with different magnetic behaviors, and a series of Cu dinuclear complexes with a broad range of magnetic coupling values. Both HSE and LC-ωPBE provide a significant improvement to standard hybrids such as the well-known hybrid Becke-3-parameters exchange with Lee-Yang-Parr correlation (B3LYP) functional. Nevertheless, the performance of these two range-separated hybrid functionals is different: HSE overestimates antiferromagnetic and ferromagnetic interactions in Cu dinuclear complexes (although significantly less than B3LYP), whereas LC-ωPBE treats ferro- and antiferromagnetic couplings on a much more balanced way. The increased accuracy of LC-ωPBE suggests that the inclusion of 100% Hartree-Fock exchange considered in the definition of this long-range corrected hybrid functional has important consequences for an accurate description of exchange and correlation effects on the electronic structure of open shell systems. On the other hand, HSE, which was developed with periodic systems in mind, also performs quite well (and better than B3LYP) thus opening the possibility of magnetic coupling studies in metal oxides and other challenging solids.

  16. Protein-functionalized magnetic iron oxide nanoparticles: time efficient potential-water treatment

    NASA Astrophysics Data System (ADS)

    Okoli, Chuka; Boutonnet, Magali; Järås, Sven; Rajarao-Kuttuva, Gunaratna

    2012-10-01

    Recent advances in nanoscience suggest that the existing issues involving water quality could be resolved or greatly improved using nanomaterials, especially magnetic iron oxide nanoparticles. Magnetic nanoparticles have been synthesized for the development and use, in association with natural coagulant protein for water treatment. The nanoparticles size, morphology, structure, and magnetic properties were characterized by transmission electron microscope, X-ray diffraction, and superconducting quantum interference device magnetometry. Purified Moringa oleifera protein was attached onto microemulsions-prepared magnetic iron oxide nanoparticles (ME-MION) to form stable protein-functionalized magnetic nanoparticles (PMO+ME-MION). The turbidity removal efficiency in both synthetic and surface water samples were investigated and compared with the commonly used synthetic coagulant (alum) as well as PMO. More than 90 % turbidity could be removed from the surface waters within 12 min by magnetic separation of PMO+ME-MION; whereas gravimetrically, 70 % removal in high and low turbid waters can be achieved within 60 min. In contrast, alum requires 180 min to reduce the turbidity of low turbid water sample. These data support the advantage of separation with external magnetic field (magnetophoresis) over gravitational force. Time kinetics studies show a significant enhancement in ME-MION efficiency after binding with PMO implying the availability of large surface of the ME-MION. The coagulated particles (impurities) can be removed from PMO+ME-MION by washing with mild detergent or cleaning solution. To our knowledge, this is the first report on surface water turbidity removal using protein-functionalized magnetic nanoparticle.

  17. Magnetic two-photon scattering and two-photon emission - Cross sections and redistribution functions

    NASA Technical Reports Server (NTRS)

    Alexander, S. G.; Meszaros, P.

    1991-01-01

    The magnetic two-photon scattering cross section is discussed within the framework of QED, and the corresponding scattering redistribution function for this process and its inverse, as well as the scattering source function are calculated explicitly. In a similar way, the magnetic two-photon emission process which follows the radiative excitation of Landau levels above ground is calculated. The two-photon scattering and two-photon emission are of the same order as the single-photon magnetic scattering. All three of these processes, and in optically thick cases also their inverses, are included in radiative transport calculations modeling accreting pulsars and gamma-ray bursters. These processes play a prominent role in determining the relative strength of the first two cyclotron harmonics, and their effects extend also to the higher harmonics.

  18. Procedural learning in schizophrenia investigated with functional magnetic resonance imaging.

    PubMed

    Zedkova, Lenka; Woodward, Neil D; Harding, Ian; Tibbo, Phil G; Purdon, Scot E

    2006-12-01

    A cerebral basis for the acquisition and retention of procedural knowledge in schizophrenia was examined with 1.5 T functional MRI during an embedded sequence Serial Reaction Time Task (SRTT) in 10 chronic medicated patients and 15 healthy controls. Comparable procedural learning was observed in both groups, suggesting that the impairment reported in previous schizophrenia samples may not be robust. Consistent with previous fMRI reports, procedural learning in the control group was associated with activity in the dorsal striatum, anterior cingulate, parietal cortex and frontal cortex. Greater procedural learning related activity was observed in the control relative to the schizophrenia group in the bilateral frontal, left parietal and bilateral caudate regions. Patients did not activate frontal or parietal areas while responding to the embedded sequence within the SRTT, but greater activation during procedural learning was observed relative to the control sample in the right anterior cingulate, left globus pallidus and the right superior temporal gyrus. Thus, despite comparable instantiation of procedural learning in schizophrenia, the cerebral activation associated with this cognitive skill was abnormal. The paucity of activity in bilateral frontal cortex, left parietal cortex and bilateral caudate nucleus may represent cerebral dysfunction associated with schizophrenia, whereas the hyperactivation of the right superior temporal gyrus, the right anterior cingulate cortex and the left globus pallidus may represent a compensatory cerebral action capable of facilitating near-normal task performance. The results are thus consistent with a neurodevelopmental pathology impinging on fronto-subcortical circuitry.

  19. Gold-functionalized magnetic nanoparticles restrict growth of Pseudomonas aeruginosa.

    PubMed

    Niemirowicz, Katarzyna; Swiecicka, Izabela; Wilczewska, Agnieszka Z; Misztalewska, Iwona; Kalska-Szostko, Beata; Bienias, Kamil; Bucki, Robert; Car, Halina

    2014-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) and their derivatives (aminosilane and gold-coated) have been widely investigated in numerous medical applications, including their potential to act as antibacterial drug carriers that may penetrate into bacteria cells and biofilm mass. Pseudomonas aeruginosa is a frequent cause of infection in hospitalized patients, and significant numbers of currently isolated clinical strains are resistant to standard antibiotic therapy. Here we describe the impact of three types of SPIONs on the growth of P. aeruginosa during long-term bacterial culture. Their size, structure, and physicochemical properties were determined using transmission electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy. We observed significant inhibition of P. aeruginosa growth in bacterial cultures continued over 96 hours in the presence of gold-functionalized nanoparticles (Fe₃O₄@Au). At the 48-hour time point, growth of P. aeruginosa, as assessed by the number of colonies grown from treated samples, showed the highest inhibition (decreased by 40%). These data provide strong evidence that Fe₃O₄@Au can dramatically reduce growth of P. aeruginosa and provide a platform for further study of the antibacterial activity of this nanomaterial.

  20. Advanced Magnetic Resonance Imaging techniques to probe muscle structure and function

    NASA Astrophysics Data System (ADS)

    Malis, Vadim

    Structural and functional Magnetic Resonance Imaging (MRI) studies of skeletal muscle allow the elucidation of muscle physiology under normal and pathological conditions. Continuing on the efforts of the Muscle Imaging and Modeling laboratory, the focus of the thesis is to (i) extend and refine two challenging imaging modalities: structural imaging using Diffusion Tensor Imaging (DTI) and functional imaging based on Velocity Encoded Phase Contrast Imaging (VE-PC) and (ii) apply these methods to explore age related structure and functional differences of the gastrocnemius muscle. Diffusion Tensor Imaging allows the study of tissue microstructure as well as muscle fiber architecture. The images, based on an ultrafast single shot Echo Planar Imaging (EPI) sequence, suffer from geometric distortions and low signal to noise ratio. A processing pipeline was developed to correct for distortions and to improve image Signal to Noise Ratio (SNR). DTI acquired on a senior and young cohort of subjects were processed through the pipeline and differences in DTI derived indices and fiber architecture between the two cohorts were explored. The DTI indices indicated that at the microstructural level, fiber atrophy was accompanied with a reduction in fiber volume fraction. At the fiber architecture level, fiber length and pennation angles decreased with age that potentially contribute to the loss of muscle force with age. Velocity Encoded Phase Contrast imaging provides tissue (e.g. muscle) velocity at each voxel which allows the study of strain and Strain Rate (SR) under dynamic conditions. The focus of the thesis was to extract 2D strain rate tensor maps from the velocity images and apply the method to study age related differences. The tensor mapping can potentially provide unique information on the extracellular matrix and lateral transmission the role of these two elements has recently emerged as important determinants of force loss with age. In the cross sectional study on

  1. Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications

    PubMed Central

    Wu, Wei; Wu, Zhaohui; Yu, Taekyung; Jiang, Changzhong; Kim, Woo-Sik

    2015-01-01

    This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed. PMID:27877761

  2. Density functional theory with alternative spin densities: application to magnetic systems with localized spins.

    PubMed

    Pérez-Jiménez, Angel J; Pérez-Jordá, José M; Illas, Francesc

    2004-01-01

    A new method to improve the excess spin density obtained from unrestricted Hartree-Fock wave functions in terms of natural orbitals is proposed. Using this modified excess spin density to evaluate the correlation energy by means of density functionals leads to large improvements in the computed magnetic coupling constants of several materials without need to modify the exchange contribution. This is important because it reconciles the density functional theory description with the one provided by multi-determinant wave functions. Using the present approach, the leading contribution to the magnetic coupling constant arises from electron correlation effects. The performance of the new method is illustrated on various materials including high-critical-temperature superconductors parent compounds.

  3. Dual functional AuNRs@MnMEIOs nanoclusters for magnetic resonance imaging and photothermal therapy.

    PubMed

    Chuang, Yao-Chen; Lin, Chia-Jung; Lo, Shih-Feng; Wang, Jei-Lin; Tzou, Shey-Cherng; Yuan, Shyng-Shiou; Wang, Yun-Ming

    2014-05-01

    A novel dual functional theranosis platform is developed based on manganese magnetism-engineered iron oxide (MnMEIO) and gold nanorods (AuNRs) to combine magnetic resonance (MR) imaging and photothermal therapy in one nanocluster. The platform showed improved T2-weighted MR imaging and exhibited a near-infrared (NIR) induced temperature elevation due to the unique characteristics of AuNRs@MnMEIOs nanoclusters. The obtained dual functional spherical-shaped nanoclusters showed low cytotoxicity, and high cellular uptake efficiency. The AuNRs@MnMEIOs nanoclusters also demonstrated a 1.9 and 2.2 folds r2 relaxivity value higher than those of monodispersed MnMEIO and Resovist. In addition, in vivo MR imaging study found that the contrast enhancements were - 70.4 ± 4.3% versus - 7.5 ± 3.0% in Her-2/neu overexpression tumors as compared to the control tumors. More importantly, NIR laser irradiation to the tumor site resulted in outstanding photothermal therapeutic efficacy and without damage to the surrounding tissue. In additional, the prepared dual functional AuNRs@MnMEIOs display high stability and furthermore disperse even in the presence of external magnet, showing that AuNRs@MnMEIOs nanoclusters can be manipulated by an external magnetic field. Therefore, such nanoclusters combined MR imaging and photothermal therapeutic functionality can be developed as a promising nanosystem for effective cancer diagnosis and therapy.

  4. Functional Magnetic Resonance Imaging of Cognitive Processing in Young Adults with Down Syndrome

    ERIC Educational Resources Information Center

    Jacola, Lisa M.; Byars, Anna W.; Chalfonte-Evans, Melinda; Schmithorst, Vincent J.; Hickey, Fran; Patterson, Bonnie; Hotze, Stephanie; Vannest, Jennifer; Chiu, Chung-Yiu; Holland, Scott K.; Schapiro, Mark B.

    2011-01-01

    The authors used functional magnetic resonance imaging (fMRI) to investigate neural activation during a semantic-classification/object-recognition task in 13 persons with Down syndrome and 12 typically developing control participants (age range = 12-26 years). A comparison between groups suggested atypical patterns of brain activation for the…

  5. Hyperpolarized Functional Magnetic Resonance of Murine Skeletal Muscle Enabled by Multiple Tracer-Paradigm Synchronizations

    PubMed Central

    Leftin, Avigdor; Roussel, Tangi; Frydman, Lucio

    2014-01-01

    Measuring metabolism's time- and space-dependent responses upon stimulation lies at the core of functional magnetic resonance imaging. While focusing on water's sole resonance, further insight could arise from monitoring the temporal responses arising from the metabolites themselves, in what is known as functional magnetic resonance spectroscopy. Performing these measurements in real time, however, is severely challenged by the short functional timescales and low concentrations of natural metabolites. Dissolution dynamic nuclear polarization is an emerging technique that can potentially alleviate this, as it provides a massive sensitivity enhancement allowing one to probe low-concentration tracers and products in a single-scan. Still, conventional implementations of this hyperpolarization approach are not immediately amenable to the repeated acquisitions needed in real-time functional settings. This work proposes a strategy for functional magnetic resonance of hyperpolarized metabolites that bypasses this limitation, and enables the observation of real-time metabolic changes through the synchronization of stimuli-triggered, multiple-bolus injections of the metabolic tracer 13C1-pyruvate. This new approach is demonstrated with paradigms tailored to reveal in vivo thresholds of murine hind-limb skeletal muscle activation, involving the conversion of 13C1-pyruvate to 13C1-lactate and 13C1-alanine. These functional hind-limb studies revealed that graded skeletal muscle stimulation causes commensurate increases in glycolytic metabolism in a frequency- and amplitude-dependent fashion, that can be monitored on the seconds/minutes timescale using dissolution dynamic nuclear polarization. Spectroscopic imaging further allowed the in vivo visualization of uptake, transformation and distribution of the tracer and products, in fast-twitch glycolytic and in slow-twitch oxidative muscle fiber groups. While these studies open vistas in time and sensitivity for metabolic

  6. Hyperpolarized functional magnetic resonance of murine skeletal muscle enabled by multiple tracer-paradigm synchronizations.

    PubMed

    Leftin, Avigdor; Roussel, Tangi; Frydman, Lucio

    2014-01-01

    Measuring metabolism's time- and space-dependent responses upon stimulation lies at the core of functional magnetic resonance imaging. While focusing on water's sole resonance, further insight could arise from monitoring the temporal responses arising from the metabolites themselves, in what is known as functional magnetic resonance spectroscopy. Performing these measurements in real time, however, is severely challenged by the short functional timescales and low concentrations of natural metabolites. Dissolution dynamic nuclear polarization is an emerging technique that can potentially alleviate this, as it provides a massive sensitivity enhancement allowing one to probe low-concentration tracers and products in a single-scan. Still, conventional implementations of this hyperpolarization approach are not immediately amenable to the repeated acquisitions needed in real-time functional settings. This work proposes a strategy for functional magnetic resonance of hyperpolarized metabolites that bypasses this limitation, and enables the observation of real-time metabolic changes through the synchronization of stimuli-triggered, multiple-bolus injections of the metabolic tracer 13C1-pyruvate. This new approach is demonstrated with paradigms tailored to reveal in vivo thresholds of murine hind-limb skeletal muscle activation, involving the conversion of 13C1-pyruvate to 13C1-lactate and 13C1-alanine. These functional hind-limb studies revealed that graded skeletal muscle stimulation causes commensurate increases in glycolytic metabolism in a frequency- and amplitude-dependent fashion, that can be monitored on the seconds/minutes timescale using dissolution dynamic nuclear polarization. Spectroscopic imaging further allowed the in vivo visualization of uptake, transformation and distribution of the tracer and products, in fast-twitch glycolytic and in slow-twitch oxidative muscle fiber groups. While these studies open vistas in time and sensitivity for metabolic

  7. Operant-contingency-based preparation of children for functional magnetic resonance imaging.

    PubMed Central

    Slifer, Keith J; Koontz, Kristine L; Cataldo, Michael F

    2002-01-01

    Functional magnetic resonance imaging (fMRI) is used to study brain function during behavioral tasks. The participation of pediatric subjects is problematic because reliable task performance and control of head movement are simultaneously required. Differential reinforcement decreased head motion and improved vigilance task performance in 4 children (2 with behavioral disorders) undergoing simulated fMRI scans. Results show that behavior analysis techniques can improve child cooperation during fMRI procedures. PMID:12102139

  8. Relative sensitivity of magnetic resonance spectroscopy and quantitative magnetic resonance imaging to cognitive function among nondemented individuals infected with HIV.

    PubMed

    Paul, Robert H; Ernst, Thomas; Brickman, Adam M; Yiannoutsos, Constantin T; Tate, David F; Cohen, Ronald A; Navia, Bradford A

    2008-09-01

    In the present study, we examined the relationships among cognitive function, magnetic resonance spectroscopy (MRS) brain metabolite indices measured in the basal ganglia, and quantitative magnetic resonance imaging (MRI) of the caudate nucleus and the putamen in the earliest stages of HIV-related cognitive involvement. Participants included 22 HIV-positive individuals and 20 HIV-negative individuals. HIV-positive individuals performed significantly more poorly than the HIV-negative individuals on several cognitive measures. In addition, the choline/creatine ratio was significantly higher and the N-acetyl aspartate/choline ratio was significantly lower among HIV patients. The caudate and putamen sizes were smaller among HIV-positive patients compared with controls; however, the differences did not reach statistical significance. Correlation analyses revealed associations between cognitive function and select MRS indices. In addition, caudate size was significantly correlated with performances on higher-order thinking tests whereas putamen size was significantly correlated with performances on motor tests. The results suggest that MRS differences are more pronounced than area size differences between seropositive and seronegative individuals in mild stages of HIV-related cognitive impairment. However, basal ganglia size remains an important contributor to cognitive status in this population. Longitudinal studies are needed to determine the evolution of these imaging correlates of HIV-cognitive impairment in HIV.

  9. SUPERCONDUCTING COMBINED FUNCTION MAGNET SYSTEM FOR J-PARC NEUTRINO EXPERIMENT.

    SciTech Connect

    OGITSU, T.; AJIMA, Y.; ANERELLA, M.; ESCALLIER, J.; GANETIS, G.; GUPTA, R.; HAGEDOM, D.; HARRISON, M.; HIGASHI, N.; IWAMOTO, Y.; ICHIKAWA, A.; JAIN, A.; KIMURA, N.; KOBAYASHI, T.; MAKIDA, Y.; MURATORE, J.; NAKAMOTO, T.; OHHATA, H.; TAKASAKI, N.; TANAKA, K.; TERASHIMA, A.; YAMOMOTO, A.; OBANA, T.; PARKER, B.; WANDERER, P.

    2004-10-03

    The J-PARC Neutrino Experiment, the construction of which starts in JFY 2004, will use a superconducting magnet system for its primary proton beam line. The system, which bends the 50 GeV 0.75 MW proton beam by about 80 degrees, consists of 28 superconducting combined function magnets. The magnets utilize single layer left/right asymmetric coils that generate a dipole field of 2.6 T and a quadrupole field of 18.6 T/m with the operation current of about 7.35 kA. The system also contains a few conduction cooled superconducting corrector magnets that serve as vertical and horizontal steering magnets. All the magnets are designed to provide a physical beam aperture of 130 mm in order to achieve a large beam acceptance. Extensive care is also required to achieve safe operation with the high power proton beam. The paper summarizes the system design as well as some safety analysis results.

  10. Comparison of navigated transcranial magnetic stimulation and functional magnetic resonance imaging for preoperative mapping in rolandic tumor surgery.

    PubMed

    Coburger, Jan; Musahl, Christian; Henkes, Hans; Horvath-Rizea, Diana; Bittl, Markus; Weissbach, Claudia; Hopf, Nikolai

    2013-01-01

    Navigated transcranial magnetic stimulation (nTMS) is a novel tool for preoperative functional mapping. It detects eloquent cortical areas directly, comparable to intraoperative direct cortical stimulation (DCS). The aim of this study was to evaluate the advantage of nTMS in comparison with functional magnetic resonance imaging (fMRI) in the clinical setting. Special focus was placed on accuracy of motor cortex localization in patients with rolandic lesions. Thirty consecutive patients were enrolled in the study. All patients received an fMRI and nTMS examination preoperatively. Feasibility of the technique and spatial resolution of upper and lower extremity cortical mapping were compared with fMRI. Consistency of preoperative mapping with intraoperative DCS was assessed via the neuronavigation system. nTMS was feasible in all 30 patients. fMRI was impossible in 7 out of 30 patients with special clinical conditions, pediatric patients, central vascular lesions, or compliance issues. The mean accuracy to localize motor cortex of nTMS was higher than in fMRI. In the subgroup of intrinsic tumors, nTMS produced statistically significant higher accuracy scores of the lower extremity localization than fMRI. fMRI failed to localize hand or leg areas in 6 out of 23 cases. Using nTMS, a preoperative localization of the central sulcus was possible in all patients. Verification of nTMS motor cortex localization with DCS was achieved in all cases. The fMRI localization of the hand area proved to be postcentral in one case. nTMS has fewer restrictions for preoperative functional mapping than fMRI and requires only a limited level of compliance. nTMS scores higher on the accuracy scale than fMRI. nTMS represents a highly valuable supplement for the preoperative functional planning in the clinical routine.

  11. Magnetic assembly of transparent and conducting graphene-based functional composites

    PubMed Central

    Le Ferrand, Hortense; Bolisetty, Sreenath; Demirörs, Ahmet F.; Libanori, Rafael; Studart, André R.; Mezzenga, Raffaele

    2016-01-01

    Innovative methods producing transparent and flexible electrodes are highly sought in modern optoelectronic applications to replace metal oxides, but available solutions suffer from drawbacks such as brittleness, unaffordability and inadequate processability. Here we propose a general, simple strategy to produce hierarchical composites of functionalized graphene in polymeric matrices, exhibiting transparency and electron conductivity. These are obtained through protein-assisted functionalization of graphene with magnetic nanoparticles, followed by magnetic-directed assembly of the graphene within polymeric matrices undergoing sol–gel transitions. By applying rotating magnetic fields or magnetic moulds, both graphene orientation and distribution can be controlled within the composite. Importantly, by using magnetic virtual moulds of predefined meshes, graphene assembly is directed into double-percolating networks, reducing the percolation threshold and enabling combined optical transparency and electrical conductivity not accessible in single-network materials. The resulting composites open new possibilities on the quest of transparent electrodes for photovoltaics, organic light-emitting diodes and stretchable optoelectronic devices. PMID:27354243

  12. A multi-functional testing instrument for heat assisted magnetic recording media

    SciTech Connect

    Yang, H. Z. Chen, Y. J.; Leong, S. H.; An, C. W.; Ye, K. D.; Hu, J. F.; Yin, M. J.

    2014-05-07

    With recent developments in heat assisted magnetic recording (HAMR), characterization of HAMR media is becoming very important. We present a multi-functional instrument for testing HAMR media, which integrates HAMR writing, reading, and a micro-magneto-optic Kerr effect (μ-MOKE) testing function. A potential application of the present instrument is to make temperature dependent magnetic property measurement using a pump-probe configuration. In the measurement, the media is heated up by a heating (intense) beam while a testing (weak) beam is overlapped with the heating beam for MOKE measurement. By heating the media with different heating beam power, magnetic measurements by MOKE at different temperatures can be performed. Compared to traditional existing tools such as the vibrating sample magnetometer, the present instrument provides localized and efficient heating at the measurement spot. The integration of HAMR writing and μ-MOKE system can also facilitate a localized full investigation of the magnetic media by potential correlation of HAMR head independent write/read performance to localized magnetic properties.

  13. Phonon and magnetic structure in δ-plutonium from density-functional theory

    DOE PAGES

    Söderlind, Per; Zhou, F.; Landa, A.; ...

    2015-10-30

    We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure andmore » (ii) the disordered-local-moment (DLM) method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, However, the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments.« less

  14. Stationary electron velocity distribution function in crossed electric and magnetic fields with collisions

    SciTech Connect

    Shagayda, Andrey

    2012-08-15

    Analytical studies and numerical simulations show that the electron velocity distribution function in a Hall thruster discharge with crossed electric and magnetic fields is not Maxwellian. This is due to the fact that the mean free path between collisions is greater than both the Larmor radius and the characteristic dimensions of the discharge channel. However in numerical models of Hall thrusters, a hydrodynamic approach is often used to describe the electron dynamics, because discharge simulation in a fully kinetic approach requires large computing resources and is time consuming. A more accurate modeling of the electron flow in the hydrodynamic approximation requires taking into account the non-Maxwellian character of the distribution function and finding its moments, an approach that reflects the properties of electrons drifting in crossed electric and magnetic fields better than the commonly used Euler or Navier-Stokes approximations. In the present paper, an expression for the electron velocity distribution function in rarefied spatially homogeneous stationary plasma with crossed electric and magnetic fields and predominance of collisions with heavy particles is derived in the relaxation approximation. The main moments of the distribution function including longitudinal and transversal temperatures, the components of the viscous stress tensor, and of the heat flux vector are calculated. Distinctive features of the hydrodynamic description of electrons with a strongly non-equilibrium distribution function and the prospects for further development of the proposed approach for calculating the distribution function in spatially inhomogeneous plasma are discussed.

  15. Development of Small-sized Fluid Control Valve with Self-holding Function Using Permanent Magnet

    NASA Astrophysics Data System (ADS)

    Akagi, Tetsuya; Dohta, Shujiro; Ueda, Hirofumi

    Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. In such a control system, an actuator and a driving device such as a control valve are mounted on the human body. In this condition, the size and weight of the control valve become serious problems. At the same time, the valve should be operated with lower energy consumption because of using a limited electrical power. The typical electro magnetic solenoid valve drives its spool using a larger solenoid to open the valve. The complex construction of the valve for sealing makes its miniaturization and the fabrication of a low cost valve more difficult. In addition, the solenoid in the valve consumes more electrical power while the valve is kept opening. The purpose of our study is to develop a small-sized, lightweight, lower energy consumption and flexible control valve that can be safe enough to mount on the human body at a lower cost. In our pervious study, we proposed and tested the control valve that can open using a vibration motor. In this study, we propose and test a new type of fluid control valve with a self-holding function. The new valve uses a permanent magnet ball. It has a cylindrical magnet and two solenoids. The self-holding function of the valve is done as follows. When one side of the solenoid is stimulated by the current momentarily, the solenoid gives a repulsive force to the cylindrical magnet. The magnet moves toward the opposite side of the solenoid and is attracted to the iron core. Then, the magnet ball moves toward the cylindrical magnet and opens the orifice. The valve can keep open without electrical energy. As a result, the valve with the extremely lower energy consumption can be developed.

  16. Electronic structure and magnetism in sodium nickelate: Density-functional and model studies

    NASA Astrophysics Data System (ADS)

    Meskine, H.; Satpathy, S.

    2005-12-01

    The electronic structure and magnetism in NaNiO2 are studied from density-functional calculations and by solving model Hamiltonians, suggested from the density-functional results, to understand the magnetic exchange. The density-functional calculations within the LSDA approximation yield a layered antiferromagnetic solution with ferro-orbital ordering of the Ni(d) orbitals arising from the Jahn-Teller distortion around the Ni3+ ion in agreement with the orbital ordering inferred from neutron diffraction. The weak ferromagnetic interaction within the layer (JF≈1meV) is caused by the 90° Ni-O-Ni exchange following the Goodenough-Kanamori-Anderson rules, while the weaker antiferromagnetic interaction between the layers (JAF≈-0.1meV) is mediated via a long Ni-O-Na-O-Ni superexchange path. In order to shed light on the differences between NaNiO2 and LiNiO2 , which show very different magnetic behaviors in spite of the similarity of their crystal structures, we examine the effect of the coupling of the alkali atom (Na) motion to the electronic degrees of freedom on the interlayer exchange JAF . A model Hamiltonian is proposed and solved by exact diagonalization and by using the variational Lang-Firsov method. We find that reducing the mass by going from Na to Li does reduce the strength of the magnetic exchange, but only by a small amount, so that the difference in mass alone cannot describe the differences in magnetic behavior between the two compounds. It is suggested that other electronic effects such as differences in orbital ordering could be responsible for the difference in magnetism between NaNiO2 and LiNiO2 .

  17. Evolution of the Red Sea Continental Margin from Integrated Analyses of Gravity, Magnetic, and Receiver Function Observations

    NASA Astrophysics Data System (ADS)

    Reed, C. A.; Mohamed, A. A.; Gao, S. S.; Mickus, K. L.; Liu, K. H.; Yu, Y.; Elsheikh, A. A.

    2014-12-01

    The development of evolutionary models and constraints for the extensional mechanisms which govern continental rifting is of fundamental significance toward understanding the breakup of continents and the role of volcanism in achieving successful rifting. To analyze the transitional nature of the Red Sea rift (RSR) passive margins and to quantify the mechanism through which extension has been accommodated, we examined a total of 3531 high-quality radial receiver functions from multiple temporary deployments in Saudi Arabia and the Levant as well as data recently acquired by the Egyptian National Seismic Network. Egypt is characterized by a relatively constant crustal thickness of approximately 37 km, while the southern Arabian Shield is roughly 35 km on average. The crust beneath the Eastern Desert of Egypt is significantly thinned with an average thickness of about 26 km. Observations of Vp/Vs across the Arabian-Nubian Shield indicate highly similar intermediate to mafic compositions, supporting well-accepted theories for juvenile arc accretion of relatively uniform makeup. Thinned crust as far as 130 km inland on the Egyptian margin indicates a highly asymmetric crustal structure across the Red Sea, supporting a model invoking simple shear extensional mechanisms. Joint modeling using satellite gravity and magnetic data with RF Moho depth constraints reveals the presence of high-density high-magnetic susceptibility mafic complexes which we interpret as volcanic margins in the northern RSR at ~25.5°N and the southern RSR at ~19.5°N. We believe the development of the northern RSR margin is accompanied by isolated volcanism associated with slow spreading rates since the Oligocene.

  18. Acquired hypofibrinogenemia: current perspectives

    PubMed Central

    Besser, Martin W; MacDonald, Stephen G

    2016-01-01

    Acquired hypofibrinogenemia is most frequently caused by hemodilution and consumption of clotting factors. The aggressive replacement of fibrinogen has become one of the core principles of modern management of massive hemorrhage. The best method for determining the patient’s fibrinogen level remains controversial, and particularly in acquired dysfibrinogenemia, could have major therapeutic implications depending on which quantification method is chosen. This review introduces the available laboratory and point-of-care methods and discusses the relative advantages and limitations. It also discusses current strategies for the correction of hypofibrinogenemia. PMID:27713652

  19. Community-acquired pneumonia.

    PubMed

    Falguera, M; Ramírez, M F

    2015-11-01

    This article not only reviews the essential aspects of community-acquired pneumonia for daily clinical practice, but also highlights the controversial issues and provides the newest available information. Community-acquired pneumonia is considered in a broad sense, without excluding certain variants that, in recent years, a number of authors have managed to delineate, such as healthcare-associated pneumonia. The latter form is nothing more than the same disease that affects more frail patients, with a greater number of risk factors, both sharing an overall common approach.

  20. Iron oxide magnetic nanoparticles with versatile surface functions based on dopamine anchors

    NASA Astrophysics Data System (ADS)

    Mazur, Mykola; Barras, Alexandre; Kuncser, Victor; Galatanu, Andrei; Zaitzev, Vladimir; Turcheniuk, Kostiantyn V.; Woisel, Patrice; Lyskawa, Joel; Laure, William; Siriwardena, Aloysius; Boukherroub, Rabah; Szunerits, Sabine

    2013-03-01

    The synthesis of multifunctional magnetic nanoparticles (MF-MPs) is one of the most active research areas in advanced materials as their multifunctional surfaces allow conjugation of biological and chemical molecules, thus making it possible to achieve target-specific diagnostic in parallel to therapeutics. We report here a simple strategy to integrate in a one-step reaction several reactive sites onto the particles. The preparation of MF-MPs is based on their simultaneous modification with differently functionalized dopamine derivatives using simple solution chemistry. The formed MF-MPs show comparable magnetic properties to those of naked nanoparticles with almost unaltered particle size of around 25 nm. The different termini, amine, azide and maleimide functions, enable further functionalization of MF-MPs by the grafting-on approach. Michael addition, Cu(i) catalyzed « click » chemistry and amidation reactions are performed on the MF-MPs integrating subsequently 6-(ferrocenyl)-hexanethiol, horseradish peroxidase (HRP) and mannose.

  1. Magnetic Gearing and a Universal Joint- Two Functions Combined Within one Gear Unit

    NASA Astrophysics Data System (ADS)

    Puchhammer, Gregor

    2013-09-01

    Strong, powerful and robust actuators suited for the harsh environmental conditions in space are needed for future missions. Electrical drives combined with magnetic gearing seem to be one of the most promising concepts. Additional functionality in magnetic wobbling gears can be gained by changing the actual working principle. By minimizing the number of functional gear stages, one additional torque transducing element has to be added. This element enables an angular displacement of the coaxial aligned input-output axis. In an extreme mode the output axis can be inclined in the opposite direction. This mode, in which gearing is no longer function, can be used for folding large structures during storage, transport, launching or shuttle.

  2. Functionalized magnetic nanowires for chemical and magneto-mechanical induction of cancer cell death

    PubMed Central

    Martínez-Banderas, Aldo Isaac; Aires, Antonio; Teran, Francisco J.; Perez, Jose Efrain; Cadenas, Jael F.; Alsharif, Nouf; Ravasi, Timothy; Cortajarena, Aitziber L.; Kosel, Jürgen

    2016-01-01

    Exploiting and combining different properties of nanomaterials is considered a potential route for next generation cancer therapies. Magnetic nanowires (NWs) have shown good biocompatibility and a high level of cellular internalization. We induced cancer cell death by combining the chemotherapeutic effect of doxorubicin (DOX)-functionalized iron NWs with the mechanical disturbance under a low frequency alternating magnetic field. (3-aminopropyl)triethoxysilane (APTES) and bovine serum albumin (BSA) were separately used for coating NWs allowing further functionalization with DOX. Internalization was assessed for both formulations by confocal reflection microscopy and inductively coupled plasma-mass spectrometry. From confocal analysis, BSA formulations demonstrated higher internalization and less agglomeration. The functionalized NWs generated a comparable cytotoxic effect in breast cancer cells in a DOX concentration-dependent manner, (~60% at the highest concentration tested) that was significantly different from the effect produced by free DOX and non-functionalized NWs formulations. A synergistic cytotoxic effect is obtained when a magnetic field (1 mT, 10 Hz) is applied to cells treated with DOX-functionalized BSA or APTES-coated NWs, (~70% at the highest concentration). In summary, a bimodal method for cancer cell destruction was developed by the conjugation of the magneto-mechanical properties of iron NWs with the effect of DOX producing better results than the individual effects. PMID:27775082

  3. Functionalized magnetic nanowires for chemical and magneto-mechanical induction of cancer cell death

    NASA Astrophysics Data System (ADS)

    Martínez-Banderas, Aldo Isaac; Aires, Antonio; Teran, Francisco J.; Perez, Jose Efrain; Cadenas, Jael F.; Alsharif, Nouf; Ravasi, Timothy; Cortajarena, Aitziber L.; Kosel, Jürgen

    2016-10-01

    Exploiting and combining different properties of nanomaterials is considered a potential route for next generation cancer therapies. Magnetic nanowires (NWs) have shown good biocompatibility and a high level of cellular internalization. We induced cancer cell death by combining the chemotherapeutic effect of doxorubicin (DOX)-functionalized iron NWs with the mechanical disturbance under a low frequency alternating magnetic field. (3-aminopropyl)triethoxysilane (APTES) and bovine serum albumin (BSA) were separately used for coating NWs allowing further functionalization with DOX. Internalization was assessed for both formulations by confocal reflection microscopy and inductively coupled plasma-mass spectrometry. From confocal analysis, BSA formulations demonstrated higher internalization and less agglomeration. The functionalized NWs generated a comparable cytotoxic effect in breast cancer cells in a DOX concentration-dependent manner, (~60% at the highest concentration tested) that was significantly different from the effect produced by free DOX and non-functionalized NWs formulations. A synergistic cytotoxic effect is obtained when a magnetic field (1 mT, 10 Hz) is applied to cells treated with DOX-functionalized BSA or APTES-coated NWs, (~70% at the highest concentration). In summary, a bimodal method for cancer cell destruction was developed by the conjugation of the magneto-mechanical properties of iron NWs with the effect of DOX producing better results than the individual effects.

  4. Noninvasive Microsurgery Using Aptamer-Functionalized Magnetic Microdisks for Tumor Cell Eradication.

    PubMed

    Zamay, Tatiana N; Zamay, Galina S; Belyanina, Irina V; Zamay, Sergey S; Denisenko, Valery V; Kolovskaya, Olga S; Ivanchenko, Tatiana I; Grigorieva, Valentina L; Garanzha, Irina V; Veprintsev, Dmitry V; Glazyrin, Yury E; Shabanov, Alexandr V; Prinz, Viktor Y; Seleznev, Vladimir A; Sokolov, Alexey E; Prokopenko, Vladimir S; Kim, Petr D; Gargaun, Ana; Berezovski, Maxim V; Zamay, Anna S

    2017-04-01

    Magnetomechanical cell disruption using nano- and microsized structures is a promising biomedical technology used for noninvasive elimination of diseased cells. It applies alternating magnetic field (AMF) for ferromagnetic microdisks making them oscillate and causing cell membrane disruption with cell death followed by apoptosis. In this study, we functionalized the magnetic microdisks with cell-binding DNA aptamers and guided the microdisks to recognize cancerous cells in a mouse tumor in vivo. Only 10 min of the treatment with a 100 Hz AMF was enough to eliminate cancer cells from a malignant tumor. Our results demonstrate a good perspective of using aptamer-modified magnetic microdisks for noninvasive microsurgery for tumors.

  5. Density functional investigation of the magnetic superstructure of Cu2MnSnS4

    NASA Astrophysics Data System (ADS)

    Koo, Hyun-Joo

    2012-09-01

    The cause for the ordered magnetic structure of Cu2MnSnS4 below TN=8.8 K was examined by evaluating the spin exchange interactions on the basis of density functional electronic structure calculations. The Mn-S…S-Mn super-superexchange interactions of Cu2MnSnS4 are all calculated to be antiferromagnetic. In the (2a, b, 2c) magnetic superstructure observed from the neutron diffraction, only one spin exchange contributes to the energy lowering. This makes the (2a, b, c) antiferromagnetic superstructure identical in energy with the (2a, b, 2c) antiferromagnetic superstructure, implying that the magnetic Bragg peaks of Cu2MnSnS4 below TN have contributions from both (2a, b, c) and (2a, b, 2c) superstructures.

  6. Interhemispheric neuroplasticity following limb deafferentation detected by resting-state functional connectivity magnetic resonance imaging (fcMRI) and functional magnetic resonance imaging (fMRI)

    PubMed Central

    Pawela, Christopher P.; Biswal, Bharat B.; Hudetz, Anthony G.; Li, Rupeng; Jones, Seth R.; Cho, Younghoon R.; Matloub, Hani S.; Hyde, James S.

    2009-01-01

    Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show brain reorganization following peripheral nerve injury. Subacute neuroplasticity was observed two weeks following transection of the four major nerves of the brachial plexus. Direct functional magnetic resonance imaging (fMRI) stimulation of the intact radial nerve reveals an activation pattern in the forelimb regions of the sensory and motor cortices that is significantly different from that observed in normal rats. Results of this fMRI experiment were used to determine seed voxel regions for fcMRI analysis. Intrahemispheric connectivities in the sensorimotor forelimb representations in both hemispheres are largely unaffected by deafferentation, whereas substantial disruption of interhemispheric sensorimotor cortical connectivity occurs. In addition, significant intra- and interhemispheric changes in connectivities of thalamic nuclei were found. These are the central findings of the study. They could not have been obtained from fMRI studies alone—both fMRI and fcMRI are needed. The combination provides a general marker for brain plasticity. The rat visual system was studied in the same animals as a control. No neuroplastic changes in connectivities were found in the primary visual cortex upon forelimb deafferentation. Differences were noted in regions responsible for processing multisensory visual-motor information. This incidental discovery is considered to be significant. It may provide insight into phantom limb epiphenomena. PMID:19796693

  7. Unique magnetic and thermoelectric properties of chemically functionalized narrow carbon polymers

    NASA Astrophysics Data System (ADS)

    Zberecki, K.; Wierzbicki, M.; Swirkowicz, R.; Barnaś, J.

    2017-02-01

    We analyze magnetic, transport and thermoelectric properties of narrow carbon polymers, which are chemically functionalized with nitroxide groups. Numerical calculations of the electronic band structure and the corresponding transmission function are based on density functional theory. Transport and thermoelectric parameters are calculated in the linear response regime, with particular interest in charge and spin thermopowers (charge and spin Seebeck effects). Such nanoribbons are shown to have thermoelectric properties described by large thermoelectric efficiency, which makes these materials promising from the application point of view.

  8. How the blind "see" Braille: lessons from functional magnetic resonance imaging.

    PubMed

    Sadato, Norihiro

    2005-12-01

    What does the visual cortex of the blind do during Braille reading? This process involves converting simple tactile information into meaningful patterns that have lexical and semantic properties. The perceptual processing of Braille might be mediated by the somatosensory system, whereas visual letter identity is accomplished within the visual system in sighted people. Recent advances in functional neuroimaging techniques, such as functional magnetic resonance imaging, have enabled exploration of the neural substrates of Braille reading. The primary visual cortex of early-onset blind subjects is functionally relevant to Braille reading, suggesting that the brain shows remarkable plasticity that potentially permits the additional processing of tactile information in the visual cortical areas.

  9. Acquired Brain Injury Program.

    ERIC Educational Resources Information Center

    Schwartz, Stacey Hunter

    This paper reviews the Acquired Brain Injury (ABI) Program at Coastline Community College (California). The ABI Program is a two-year, for-credit educational curriculum designed to provide structured cognitive retraining for adults who have sustained an ABI due to traumatic (such as motor vehicle accident or fall) or non-traumatic(such as…

  10. Ion energy-angle distribution functions at the plasma-material interface in oblique magnetic fields

    SciTech Connect

    Khaziev, Rinat; Curreli, Davide

    2015-04-15

    The ion energy-angle distribution (IEAD) at the wall of a magnetized plasma is of fundamental importance for the determination of the material processes occurring at the plasma-material interface, comprising secondary emissions and material sputtering. Here, we present a numerical characterization of the IEAD at the wall of a weakly collisional magnetized plasma with the magnetic field inclined at an arbitrary angle with respect to the wall. The analysis has been done using two different techniques: (1) a fluid-Monte Carlo method, and (2) particle-in-cell simulations, the former offering a fast but approximate method for the determination of the IEADs, the latter giving a computationally intensive but self-consistent treatment of the plasma behavior from the quasi-neutral region to the material boundary. The two models predict similar IEADs, whose similarities and differences are discussed. Data are presented for magnetic fields inclined at angles from normal to grazing incidence (0°–85°). We show the scaling factors of the average and peak ion energy and trends of the pitch angle at the wall as a function of the magnetic angle, for use in the correlation of fluid plasma models to material models.

  11. Simple enrichment of thiol-containing biomolecules by using zinc(II)-cyclen-functionalized magnetic beads.

    PubMed

    Fujioka, Haruto; Tsunehiro, Masaya; Kawaguchi, Maho; Kuramoto, Yasuhiro; Kurosaki, Hiromasa; Hieda, Yuhzo; Kinoshita-Kikuta, Emiko; Kinoshita, Eiji; Koike, Tohru

    2014-07-01

    A simple and efficient method based on magnetic-bead technology has been developed for the enrichment of thiol-containing biomolecules, such as l-glutathione and cysteine-containing peptides. The thiol-binding site on the bead is a mononuclear complex of zinc(II) with 1,4,7,10-tetraazacyclododecane (cyclen); this is linked to a hydrophilic cross-linked agarose coating on a particle that has a magnetic core. All steps for the thiol-affinity separation are conducted in aqueous buffers with 0.10 mL of the magnetic beads in a 1.5 mL microtube. The entire separation protocol for thiol-containing compounds, from addition to elution, requires less than one hour per sample, provided the buffers and the zinc(II)-cyclen-functionalized magnetic beads have been prepared in advance. The thiol-affinity magnetic beads are reusable at least 15 times without a decrease in their thiol-binding ability, and they are stable for six months at room temperature.

  12. Electronic and magnetic properties of silicon supported organometallic molecular wires: a density functional theory (DFT) study.

    PubMed

    Liu, Xia; Tan, Yingzi; Li, Xiuling; Wu, Xiaojun; Pei, Yong

    2015-08-28

    The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to the well-studied gas phase TM-benzene molecular wires. Si-[Mn(styrene)]∞ and Si-[Cr(styrene)]∞ single molecular wires (SMWs) are a ferromagnetic semiconductor and half metal, respectively. Creation of H-atom defects on the silicon surface can introduce an impurity metallic band, which leads to novel half-metallic magnetism of a Si-[Mn(styrene)]∞ system. Moreover, double molecular wires (DMWs) containing two identical or hetero SMWs are theoretically designed. The [Mn(styrene)]∞-[Cr(styrene)]∞ DMW exhibits half-metallic magnetism where the spin-up and spin-down channels are contributed by two single molecular wires. Finally, we demonstrate that introducing a TM-defect may significantly affect the electronic structure and magnetic properties of molecular wires. These studies provide new insights into the structure and properties of surface supported 1-D sandwiched molecular wires and may inspire the future experimental synthesis of substrate confined organometallic sandwiched molecular wires.

  13. Ion energy-angle distribution functions at the plasma-material interface in oblique magnetic fields

    NASA Astrophysics Data System (ADS)

    Khaziev, Rinat; Curreli, Davide

    2015-04-01

    The ion energy-angle distribution (IEAD) at the wall of a magnetized plasma is of fundamental importance for the determination of the material processes occurring at the plasma-material interface, comprising secondary emissions and material sputtering. Here, we present a numerical characterization of the IEAD at the wall of a weakly collisional magnetized plasma with the magnetic field inclined at an arbitrary angle with respect to the wall. The analysis has been done using two different techniques: (1) a fluid-Monte Carlo method, and (2) particle-in-cell simulations, the former offering a fast but approximate method for the determination of the IEADs, the latter giving a computationally intensive but self-consistent treatment of the plasma behavior from the quasi-neutral region to the material boundary. The two models predict similar IEADs, whose similarities and differences are discussed. Data are presented for magnetic fields inclined at angles from normal to grazing incidence (0°-85°). We show the scaling factors of the average and peak ion energy and trends of the pitch angle at the wall as a function of the magnetic angle, for use in the correlation of fluid plasma models to material models.

  14. Functionalized ultrasound-propelled magnetically guided nanomotors: toward practical biomedical applications.

    PubMed

    Garcia-Gradilla, Victor; Orozco, Jahir; Sattayasamitsathit, Sirilak; Soto, Fernando; Kuralay, Filiz; Pourazary, Ashley; Katzenberg, Adlai; Gao, Wei; Shen, Yufeng; Wang, Joseph

    2013-10-22

    Magnetically guided ultrasound-powered nanowire motors, functionalized with bioreceptors and a drug-loaded polymeric segment, are described for "capture and transport" and drug-delivery processes. These high-performance fuel-free motors display advanced capabilities and functionalities, including magnetic guidance, coordinated aligned movement, cargo towing, capture and isolation of biological targets, drug delivery, and operation in real-life biological and environmental media. The template-prepared three-segment Au-Ni-Au nanowire motors are propelled acoustically by mechanical waves produced by a piezoelectric transducer. An embedded nickel segment facilitates a magnetically guided motion as well as transport of large "cargo" along predetermined trajectories. Substantial improvement in the speed and power is realized by the controlled concavity formation at the end of the motor nanowire using a sphere lithography protocol. Functionalization of the Au segments with lectin and antiprotein A antibody bioreceptors allows capture and transport of E. coli and S. aureus bacteria, respectively. Potential therapeutic applications are illustrated in connection to the addition of a pH-sensitive drug-loaded polymeric (PPy-PSS) segment. The attractive capabilities of these fuel-free acoustically driven functionalized Au-Ni-Au nanowires, along with the simple preparation procedure and minimal adverse effects of ultrasonic waves, make them highly attractive for diverse in vivo biomedical applications.

  15. Design and synthesis of polymer-functionalized NIR fluorescent dyes--magnetic nanoparticles for bioimaging.

    PubMed

    Yen, Swee Kuan; Jańczewski, Dominik; Lakshmi, Jeeva Lavanya; Dolmanan, Surani Bin; Tripathy, Sudhiranjan; Ho, Vincent H B; Vijayaragavan, Vimalan; Hariharan, Anushya; Padmanabhan, Parasuraman; Bhakoo, Kishore K; Sudhaharan, Thankiah; Ahmed, Sohail; Zhang, Yong; Tamil Selvan, Subramanian

    2013-08-27

    The fluorescent probes having complete spectral separation between absorption and emission spectra (large Stokes shift) are highly useful for solar concentrators and bioimaging. In bioimaging application, NIR fluorescent dyes have a greater advantage in tissue penetration depth compared to visible-emitting organic dyes or inorganic quantum dots. Here we report the design, synthesis, and characterization of an amphiphilic polymer, poly(isobutylene-alt-maleic anhyride)-functionalized near-infrared (NIR) IR-820 dye and its conjugates with iron oxide (Fe3O4) magnetic nanoparticles (MNPs) for optical and magnetic resonance (MR) imaging. Our results demonstrate that the Stokes shift of unmodified dye can be tuned (from ~106 to 208 nm) by the functionalization of the dye with polymer and MNPs. The fabrication of bimodal probes involves (i) the synthesis of NIR fluorescent dye (IR-820 cyanine) functionalized with ethylenediamine linker in high yield, >90%, (ii) polymer conjugation to the functionalized NIR fluorescent dye, and (iii) grafting the polymer-conjugated dyes on iron oxide MNPs. The resulting uniform, small-sized (ca. 6 nm) NIR fluorescent dye-magnetic hybrid nanoparticles (NPs) exhibit a wider emissive range (800-1000 nm) and minimal cytotoxicity. Our preliminary studies demonstrate the potential utility of these NPs in bioimaging by means of direct labeling of cancerous HeLa cells via NIR fluorescence microscopy and good negative contrast enhancement in T2-weighted MR imaging of a murine model.

  16. Hydrazide functionalized core-shell magnetic nanocomposites for highly specific enrichment of N-glycopeptides.

    PubMed

    Liu, Liting; Yu, Meng; Zhang, Ying; Wang, Changchun; Lu, Haojie

    2014-05-28

    In view of the biological significance of glycosylation for human health, profiling of glycoproteome from complex biological samples is highly inclined toward the discovery of disease biomarkers and clinical diagnosis. Nevertheless, because of the existence of glycopeptides at relatively low abundances compared with nonglycosylated peptides and glycan microheterogeneity, glycopeptides need to be highly selectively enriched from complex biological samples for mass spectrometry analysis. Herein, a new type of hydrazide functionalized core-shell magnetic nanocomposite has been synthesized for highly specific enrichment of N-glycopeptides. The nanocomposites with both the magnetic core and the polymer shell hanging high density of hydrazide groups were prepared by first functionalization of the magnetic core with polymethacrylic acid by reflux precipitation polymerization to obtain the Fe3O4@poly(methacrylic acid) (Fe3O4@PMAA) and then modification of the surface of Fe3O4@PMAA with adipic acid dihydrazide (ADH) to obtain Fe3O4@poly(methacrylic hydrazide) (Fe3O4@PMAH). The abundant hydrazide groups toward highly specific enrichment of glycopeptides and the magnetic core make it suitable for large-scale, high-throughput, and automated sample processing. In addition, the hydrophilic polymer surface can provide low nonspecific adsorption of other peptides. Compared to commercially available hydrazide resin, Fe3O4@PMAH improved more than 5 times the signal-to-noise ratio of standard glycopeptides. Finally, this nanocomposite was applied in the profiling of N-glycoproteome from the colorectal cancer patient serum. In total, 175 unique glycopeptides and 181 glycosylation sites corresponding to 63 unique glycoproteins were identified in three repeated experiments, with the specificities of the enriched glycopeptides and corresponding glycoproteins of 69.6% and 80.9%, respectively. Because of all these attractive features, we believe that this novel hydrazide functionalized

  17. Preparation of hydrazine functionalized polymer brushes hybrid magnetic nanoparticles for highly specific enrichment of glycopeptides.

    PubMed

    Huang, Guang; Sun, Zhen; Qin, Hongqiang; Zhao, Liang; Xiong, Zhichao; Peng, Xiaojun; Ou, Junjie; Zou, Hanfa

    2014-05-07

    Hydrazide chemistry is a powerful technique in glycopeptides enrichment. However, the low density of the monolayer hydrazine groups on the conventional hydrazine-functionalized magnetic nanoparticles limits the efficiency of glycopeptides enrichment. Herein, a novel magnetic nanoparticle grafted with poly(glycidyl methacrylate) (GMA) brushes was fabricated via reversible addition-fragmentation chain transfer (RAFT) polymerization, and a large amount of hydrazine groups were further introduced to the GMA brushes by ring-opening the epoxy groups with hydrazine hydrate. The resulting magnetic nanoparticles (denoted as Fe3O4@SiO2@GMA-NHNH2) demonstrated the high specificity of capturing glycopeptides from a tryptic digest of the sample comprising a standard non-glycosylated protein bovine serum albumin (BSA) and four standard glycoproteins with a weight ratio of 50 : 1, and the detection limit was as low as 130 fmol. In the analysis of a real complex biological sample, the tryptic digest of hepatocellular carcinoma, 179 glycosites were identified by the Fe3O4@SiO2@GMA-NHNH2 nanoparticles, surpassing that of 68 glycosites by Fe3O4@SiO2-single-NHNH2 (with monolayer hydrazine groups on the surface). It can be expected that the magnetic nanoparticles modified with hydrazine functionalized polymer brushes via RAFT technique will improve the specificity and the binding capacity of glycopeptides from complex samples, and show great potential in the analysis of protein glycosylation in biological samples.

  18. Amine-functionalized magnetic nanoparticles for rapid capture and removal of bacterial pathogens.

    PubMed

    Huang, Yan-Feng; Wang, Ya-Fan; Yan, Xiu-Ping

    2010-10-15

    Interest in magnetic nanoparticles for capturing bacteria arises from a variety of attributes, including the similar size of nanoparticles, magnetic behavior, and attached biomolecules such as proteins and nucleotide probes. Here we report the application of amine-functionalized magnetic nanoparticles (AF-MNPs) for rapid and efficient capture and removal of bacterial pathogens. The AF-MNPs are used without the need for any further modifications with affinity biomolecules. The positive charges on the surface of AF-MNPs can promote strong electrostatic interaction with negatively charged sites on the surface of bacterial pathogens to exhibit efficient adsorptive ability. The hydrophobic interaction between the pendant propyl group of the amine functionality and the bacteria also plays a supplementary role. The amine groups on the surface of the magnetic nanoparticle are robust and inexpensive ligands to ensure a high binding affinity to at least eight different species of Gram-positive and Gram-negative bacteria. The amount of AF-MNPs, pH of phosphate buffer solution, and ionic strength are crucial in mediating fast and effective interactions between AF-MNPs and bacteria. The AF-MNPs allow rapid removal of bacteria from water samples, food matrixes, and a urine sample with efficiency from 88.5% to 99.1%. Though amino group offers less specificity/selectivity than biomolecules such as antibodies, AF-MNPs are attractive for capturing a wide range of bacteria.

  19. Functional expression of an scFv on bacterial magnetic particles by in vitro docking

    SciTech Connect

    Sugamata, Yasuhiro; Tanaka, Tsuyoshi; Matsunaga, Tadashi; Yoshino, Tomoko

    2014-02-28

    Highlights: • We present a novel expression system called “in vitro docking” on bacterial magnetic particles. • An scFv–Fc was functionally expressed on bacterial magnetic particles of magnetotactic bacteria. • Our novel expression system on BacMPs will be effective for disulfide-bonded proteins. - Abstract: A Gram-negative, magnetotactic bacterium, Magnetospirillum magneticum AMB-1 produces nano-sized magnetic particles (BacMPs) in the cytoplasm. Although various applications of genetically engineered BacMPs have been demonstrated, such as immunoassay, ligand–receptor interaction or cell separation, by expressing a target protein on BacMPs, it has been difficult to express disulfide-bonded proteins on BacMPs due to lack of disulfide-bond formation in the cytoplasm. Here, we propose a novel dual expression system, called in vitro docking, of a disulfide-bonded protein on BacMPs by directing an immunoglobulin Fc-fused target protein to the periplasm and its docking protein ZZ on BacMPs. By in vitro docking, an scFv–Fc fusion protein was functionally expressed on BacMPs in the dimeric or trimeric form. Our novel disulfide-bonded protein expression system on BacMPs will be useful for efficient screening of potential ligands or drugs, analyzing ligand–receptor interactions or as a magnetic carrier for affinity purification.

  20. Surface functionalization of silica-coated magnetic nanoparticles for covalent attachment of cholesterol oxidase

    NASA Astrophysics Data System (ADS)

    Šulek, Franja; Drofenik, Miha; Habulin, Maja; Knez, Željko

    2010-01-01

    A systematic approach towards the fabrication of highly functionalized silica shell magnetic nanoparticles, presently used for enzyme immobilization, is herein fully presented. The synthesis of bare maghemite (γ-Fe 2O 3) nanoparticles was accomplished by thermal co-precipitation of iron ions in ammonia alkaline solution at harsh reaction conditions, respectively. Primary surface engineering of maghemite nanoparticles was successfully performed by the proper deposition of silica onto nanoparticles surface under strictly regulated reaction conditions. Next, the secondary surface functionalization of the particles was achieved by coating the particles with organosilane followed by glutaraldehyde activation in order to enhance protein immobilization. Covalent immobilization of cholesterol oxidase was attempted afterwards. The structural and magnetic properties of magnetic silica nanocomposites were characterized by TEM and vibrating sample magnetometer (VSM) instruments. X-ray diffraction measurements confirmed the spinel structure and average size of uncoated maghemite nanoparticles to be around 20 nm in diameter. SEM-EDS spectra indicated a strong signal for Si, implying the coating procedure of silica onto the particles surface to be successfully accomplished. Fourier transform infrared (FT-IR) spectra analysis confirmed the binding of amino silane molecules onto the surface of the maghemite nanoparticles mediated Si-O-Si chemical bonds. Compared to the free enzyme, the covalently bound cholesterol oxidase retained 50% of its activity. Binding of enzyme onto chemically modified magnetic nanoparticles via glutaraldehyde activation is a promising method for developing biosensing components in biomedicine.

  1. Development of magnetic resonance imaging based detection methods for beta amyloids via sialic acid-functionalized magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kouyoumdjian, Hovig

    The development of a non-invasive method for the detection of Alzheimer's disease is of high current interest, which can be critical in early diagnosis and in guiding preventive treatment of the disease. The aggregates of beta amyloids are a pathological hallmark of Alzheimer's disease. Carbohydrates such as sialic acid terminated gangliosides have been shown to play significant roles in initiation of amyloid aggregation. Herein, we report a biomimetic approach using sialic acid coated iron oxide superparamagnetic nanoparticles for in vitro detection in addition to the assessment of the in vivo mouse-BBB (Blood brain barrier) crossing of the BSA (bovine serum albumin)-modified ones. The sialic acid functionalized dextran nanoparticles were shown to bind with beta amyloids through several techniques including ELISA (enzyme linked immunosorbent assay), MRI (magnetic resonance imaging), TEM (transmission electron microscopy), gel electrophoresis and tyrosine fluorescence assay. The superparamagnetic nature of the nanoparticles allowed easy detection of the beta amyloids in mouse brains in both in vitro and ex vivo model by magnetic resonance imaging. Furthermore, the sialic acid nanoparticles greatly reduced beta amyloid induced cytotoxicity to SH-SY5Y neuroblastoma cells, highlighting the potential of the glyconanoparticles for detection and imaging of beta amyloids. Sialic acid functionalized BSA (bovine serum albumin) nanoparticles also showed significant binding to beta amyloids, through ELISA and ex vivo mouse brain MRI experiments. Alternatively, the BBB crossing was demonstrated by several techniques such as confocal microscopy, endocytosis, exocytosis assays and were affirmed by nanoparticles transcytosis assays through bEnd.3 endothelial cells. Finally, the BBB crossing was confirmed by analyzing the MRI signal of nanoparticle-injected CD-1 mice.

  2. Quantitative Assessment of Liver Function Using Gadoxetate-Enhanced Magnetic Resonance Imaging

    PubMed Central

    Georgiou, Leonidas; Penny, Jeffrey; Nicholls, Glynis; Woodhouse, Neil; Blé, François-Xavier; Hubbard Cristinacce, Penny L.; Naish, Josephine H.

    2017-01-01

    Objective The objective of this study was to use noninvasive dynamic contrast-enhanced magnetic resonance imaging (MRI) techniques to study, in vivo, the distribution and elimination of the hepatobiliary contrast agent gadoxetate in the human body and characterize the transport mechanisms involved in its uptake into hepatocytes and subsequent efflux into the bile using a novel tracer kinetic model in a group of healthy volunteers. Materials and Methods Ten healthy volunteers (age range, 18–29 years), with no history of renal or hepatic impairment, were recruited via advertisement. Participants attended 2 MRI visits (at least a week apart) with gadoxetate as the contrast agent. Dynamic contrast-enhanced MRI data were acquired for approximately 50 minutes with a 3-dimensional gradient-echo sequence in the axial plane, at a temporal resolution of 6.2 seconds. Data from regions of interest drawn in the liver were analyzed using the proposed 2-compartment uptake and efflux model to provide estimates for the uptake rate of gadoxetate in hepatocytes and its efflux rate into the bile. Reproducibility statistics for the 2 visits were obtained to examine the robustness of the technique and its dependence in acquisition time. Results Eight participants attended the study twice and were included into the analysis. The resulting images provided the ability to simultaneously monitor the distribution of gadoxetate in multiple organs including the liver, spleen, and kidneys as well as its elimination through the common bile duct, accumulation in the gallbladder, and excretion in the duodenum. The mean uptake (ki) and efflux (kef) rates in hepatocytes, for the 2 visits using the 50-minute acquisition, were 0.22 ± 0.05 and 0.017 ± 0.006/min, respectively. The hepatic extraction fraction was estimated to be 0.19 ± 0.04/min. The variability between the 2 visits within the group level (95% confidence interval; ki: ±0.02/min, kef: ±0.004/min) was lower compared with the

  3. Impact of a high magnetic field on the orientation of gravitactic unicellular organisms--a critical consideration about the application of magnetic fields to mimic functional weightlessness.

    PubMed

    Hemmersbach, Ruth; Simon, Anja; Waßer, Kai; Hauslage, Jens; Christianen, Peter C M; Albers, Peter W; Lebert, Michael; Richter, Peter; Alt, Wolfgang; Anken, Ralf

    2014-03-01

    The gravity-dependent behavior of Paramecium biaurelia and Euglena gracilis have previously been studied on ground and in real microgravity. To validate whether high magnetic field exposure indeed provides a ground-based facility to mimic functional weightlessness, as has been suggested earlier, both cell types were observed during exposure in a strong homogeneous magnetic field (up to 30 T) and a strong magnetic field gradient. While swimming, Paramecium cells were aligned along the magnetic field lines; orientation of Euglena was perpendicular, demonstrating that the magnetic field determines the orientation and thus prevents the organisms from the random swimming known to occur in real microgravity. Exposing Astasia longa, a flagellate that is closely related to Euglena but lacks chloroplasts and the photoreceptor, as well as the chloroplast-free mutant E. gracilis 1F, to a high magnetic field revealed no reorientation to the perpendicular direction as in the case of wild-type E. gracilis, indicating the existence of an anisotropic structure (chloroplasts) that determines the direction of passive orientation. Immobilized Euglena and Paramecium cells could not be levitated even in the highest available magnetic field gradient as sedimentation persisted with little impact of the field on the sedimentation velocities. We conclude that magnetic fields are not suited as a microgravity simulation for gravitactic unicellular organisms due to the strong effect of the magnetic field itself, which masks the effects known from experiments in real microgravity.

  4. Impact of a High Magnetic Field on the Orientation of Gravitactic Unicellular Organisms—A Critical Consideration about the Application of Magnetic Fields to Mimic Functional Weightlessness

    PubMed Central

    Simon, Anja; Waßer, Kai; Hauslage, Jens; Christianen, Peter C.M.; Albers, Peter W.; Lebert, Michael; Richter, Peter; Alt, Wolfgang; Anken, Ralf

    2014-01-01

    Abstract The gravity-dependent behavior of Paramecium biaurelia and Euglena gracilis have previously been studied on ground and in real microgravity. To validate whether high magnetic field exposure indeed provides a ground-based facility to mimic functional weightlessness, as has been suggested earlier, both cell types were observed during exposure in a strong homogeneous magnetic field (up to 30 T) and a strong magnetic field gradient. While swimming, Paramecium cells were aligned along the magnetic field lines; orientation of Euglena was perpendicular, demonstrating that the magnetic field determines the orientation and thus prevents the organisms from the random swimming known to occur in real microgravity. Exposing Astasia longa, a flagellate that is closely related to Euglena but lacks chloroplasts and the photoreceptor, as well as the chloroplast-free mutant E. gracilis 1F, to a high magnetic field revealed no reorientation to the perpendicular direction as in the case of wild-type E. gracilis, indicating the existence of an anisotropic structure (chloroplasts) that determines the direction of passive orientation. Immobilized Euglena and Paramecium cells could not be levitated even in the highest available magnetic field gradient as sedimentation persisted with little impact of the field on the sedimentation velocities. We conclude that magnetic fields are not suited as a microgravity simulation for gravitactic unicellular organisms due to the strong effect of the magnetic field itself, which masks the effects known from experiments in real microgravity. Key Words: Levitation—Microgravity—Gravitaxis—Gravikinesis—Gravity. Astrobiology 14, 205–215. PMID:24621307

  5. Whole brain high-resolution functional imaging at ultra high magnetic fields: an application to the analysis of resting state networks.

    PubMed

    De Martino, Federico; Esposito, Fabrizio; van de Moortele, Pierre-Francois; Harel, Noam; Formisano, Elia; Goebel, Rainer; Ugurbil, Kamil; Yacoub, Essa

    2011-08-01

    Whole-brain functional magnetic resonance imaging (fMRI) allows measuring brain dynamics at all brain regions simultaneously and is widely used in research and clinical neuroscience to observe both stimulus-related and spontaneous neural activity. Ultrahigh magnetic fields (7T and above) allow functional imaging with high contrast-to-noise ratios and improved spatial resolution and specificity compared to clinical fields (1.5T and 3T). High-resolution 7T fMRI, however, has been mostly limited to partial brain coverage with previous whole-brain applications sacrificing either the spatial or temporal resolution. Here we present whole-brain high-resolution (1, 1.5 and 2mm isotropic voxels) resting state fMRI at 7T, obtained with parallel imaging technology, without sacrificing temporal resolution or brain coverage, over what is typically achieved at 3T with several fold larger voxel volumes. Using Independent Component Analysis we demonstrate that high resolution images acquired at 7T retain enough sensitivity for the reliable extraction of typical resting state brain networks and illustrate the added value of obtaining both single subject and group maps, using cortex based alignment, of the default-mode network (DMN) with high native resolution. By comparing results between multiple resolutions we show that smaller voxels volumes (1 and 1.5mm isotropic) data result in reduced partial volume effects, permitting separations of detailed spatial features within the DMN patterns as well as a better function to anatomy correspondence.

  6. Correlation between visual function, neurodevelopmental outcome, and magnetic resonance imaging findings in infants with periventricular leucomalacia

    PubMed Central

    Cioni, G.; Bertuccelli, B.; Boldrini, A.; Canapicchi, R.; Fazzi, B.; Guzzetta, A.; Mercuri, E.

    2000-01-01

    AIM—To evaluate the correlation between visual function and neurodevelopmental outcome in children with periventricular leucomalacia at 1 and 3years.
METHOD—Visual acuity, visual field, ocular motility, and optokinetic nystagmus were tested in 29 infants with periventricular leucomalacia by brain magnetic resonance imaging. All infants also had a structured neurological examination and a Griffiths developmental assessment.
RESULTS—21 of the infants showed at least one abnormality of visual function. The degree of visual impairment—that is, the number of visual tests showing abnormal results—correlated well with the results on developmental assessment at both ages.
CONCLUSION—Multivariate analysis showed that visual impairment was the most important variable in determining the neurodevelopmental scores of these infants, more than their motor disability and the extent of their lesions on magnetic resonance imaging.

 PMID:10685987

  7. Head motion during overt language production in functional magnetic resonance imaging.

    PubMed

    Heim, Stefan; Amunts, Katrin; Mohlberg, Hartmut; Wilms, Marcus; Friederici, Angela D

    2006-04-24

    Head motion parameters (translation, rotation) during an event-related functional magnetic resonance imaging experiment of overt picture naming were investigated for two fixation conditions. We compared normal fixation with cushions and belts with the additional use of a bite-bar. Neither mean nor maximum values differed between the two conditions for any of the parameters. By applying the head motion parameters to the cytoarchitectonically defined volume of the left Brodmann area 44, we demonstrated volume overlap of 95% (normal fixation) to 100% (bite-bar) that did not differ significantly between fixation conditions. The data encourage further use of overt language production in functional magnetic resonance imaging with careful head fixation but no bite-bar.

  8. Functional magnetic resonance microscopy at single-cell resolution in Aplysia californica

    PubMed Central

    Radecki, Guillaume; Nargeot, Romuald; Jelescu, Ileana Ozana; Le Bihan, Denis; Ciobanu, Luisa

    2014-01-01

    In this work, we show the feasibility of performing functional MRI studies with single-cell resolution. At ultrahigh magnetic field, manganese-enhanced magnetic resonance microscopy allows the identification of most motor neurons in the buccal network of Aplysia at low, nontoxic Mn2+ concentrations. We establish that Mn2+ accumulates intracellularly on injection into the living Aplysia and that its concentration increases when the animals are presented with a sensory stimulus. We also show that we can distinguish between neuronal activities elicited by different types of stimuli. This method opens up a new avenue into probing the functional organization and plasticity of neuronal networks involved in goal-directed behaviors with single-cell resolution. PMID:24872449

  9. Surface functionalized nano-magnetic particles for wastewater treatment: adsorption and desorption of mercury.

    PubMed

    Tri, Pham Minh; Khim, Kwa Soo; Hidajat, K; Uddin, M S

    2009-02-01

    The present study deals with adsorption and desorption of mercury on surface functionalized nano-magnetic particles. The nano-magnetic particles (Fe3O4) were synthesized by chemical precipitation of Fe2+ and Fe3+ salts at 80 degrees C at alkaline condition and inert atmosphere. The particle surface was then functionalized in two different ways: surface charge controlled by solution pH and coating the surface with polymer (vinylpyrrolidone) with thiodiglycolic acid as the primary surfactant and 4-vinylaniline as the secondary surfactant. It was found that the adsorption of mercury was pH dependent and maximum adsorption occurred at pH of 7.5 with bare particles and at pH 10 for polymer grafted particles. Maximum adsorption of mercury was found to be 280 mg/g particle.

  10. Functional mapping of the human visual cortex by magnetic resonance imaging

    SciTech Connect

    Belliveau, J.W.; Kennedy, D.N.; McKinstry, R.C.; Buchbinder, B.R.; Weisskoff, R.M.; Cohen, M.S.; Vevea, J.M.; Brady, T.J.; Rosen, B.R. Harvard Medical School, Boston, MA )

    1991-11-01

    Knowledge of regional cerebral hemodynamics has widespread application for both physiological research and clinical assessment because of the well-established interrelation between physiological function, energy metabolism, and localized blood supply. A magnetic resonance technique was developed for quantitative imaging of cerebral hemodynamics, allowing for measurement of regional cerebral blood volume during resting and activated cognitive states. This technique was used to generate the first functional magnetic resonance amps of human task activation, by using a visual stimulus paradigm. During photic stimulation, localized increases in blood volume (32 {plus minus} 10%, n = 7 subjects) were detected in the primary visual cortex. Center-of-mass coordinates and linear extends of brain activation within the plane of the calcarine fissure are reported.

  11. Functional magnetic resonance microscopy at single-cell resolution in Aplysia californica.

    PubMed

    Radecki, Guillaume; Nargeot, Romuald; Jelescu, Ileana Ozana; Le Bihan, Denis; Ciobanu, Luisa

    2014-06-10

    In this work, we show the feasibility of performing functional MRI studies with single-cell resolution. At ultrahigh magnetic field, manganese-enhanced magnetic resonance microscopy allows the identification of most motor neurons in the buccal network of Aplysia at low, nontoxic Mn(2+) concentrations. We establish that Mn(2+) accumulates intracellularly on injection into the living Aplysia and that its concentration increases when the animals are presented with a sensory stimulus. We also show that we can distinguish between neuronal activities elicited by different types of stimuli. This method opens up a new avenue into probing the functional organization and plasticity of neuronal networks involved in goal-directed behaviors with single-cell resolution.

  12. Low-energy ion distribution functions on a magnetically quiet day at geostationary altitude /L = 7/

    NASA Technical Reports Server (NTRS)

    Singh, N.; Raitt, W. J.; Yasuhara, F.

    1982-01-01

    Ion energy and pitch angle distribution functions are examined for a magnetically quiet day using averaged data from ATS 6. For both field-aligned and perpendicular fluxes, the populations have a mixture of characteristic energies, and the distribution functions can be fairly well approximated by Maxwellian distributions over three different energy bands in the range 3-600 eV. Pitch angle distributions varying with local time, and energy distributions are used to compute total ion density. Pitch angle scattering mechanisms responsible for the observed transformation of pitch angle distribution are examined, and it is found that a magnetic noise of a certain power spectral density belonging to the electromagnetic ion cyclotron mode near the ion cyclotron frequency can be effective in trapping the field aligned fluxes by pitch angle scattering.

  13. Scalable synthesis and functionalization of cobalt nanoparticles for versatile magnetic separation and metal adsorption

    NASA Astrophysics Data System (ADS)

    Mattila, Pipsa; Heinonen, Hanna; Loimula, Kalle; Forsman, Johanna; Johansson, Leena-Sisko; Tapper, Unto; Mahlberg, Riitta; Hentze, Hans-Peter; Auvinen, Ari; Jokiniemi, Jorma; Milani, Roberto

    2014-09-01

    Magnetic cobalt nanoparticles coated with a thin carbon shell were produced by means of a scalable method based on hydrogen reduction synthesis. The presence of oxidized groups on the surface of the carbon shell enabled the reaction with alkoxysilanes bearing amino and thiol reactive functions under mild conditions, and therefore the formation of a thin functional silane layer which holds the potential for further modification in consideration of specific applications, e.g., in the separation and catalysis fields. The magnetic nanoparticles bearing surface thiol groups were also used in metal adsorption tests. These nanoparticles could efficiently adsorb not only gold from a chloride salt aqueous solution, but also several other metals when incubated in a thiocyanate-leached solution obtained from crushed printed circuit boards. The combination of a scalable production method with a simple and versatile surface modification strategy opens up a wide array of potential industrial applications in the fields of separation, sensing, and biomedical devices.

  14. Fluorochrome-functionalized magnetic nanoparticles for high-sensitivity monitoring of the polymerase chain reaction by magnetic resonance.

    PubMed

    Alcantara, David; Guo, Yanyan; Yuan, Hushan; Goergen, Craig J; Chen, Howard H; Cho, Hoonsung; Sosnovik, David E; Josephson, Lee

    2012-07-09

    Easy to find: magnetic nanoparticles bearing fluorochromes (red) that intercalate with DNA (green) form microaggregates with DNA generated by the polymerase chain reaction (PCR). These aggregates can be detected at low cycle numbers by magnetic resonance (MR).

  15. Inherited or acquired metabolic disorders.

    PubMed

    Eichler, Florian; Ratai, Eva; Carroll, Jason J; Masdeu, Joseph C

    2016-01-01

    This chapter starts with a description of imaging of inherited metabolic disorders, followed by a discussion on imaging of acquired toxic-metabolic disorders of the adult brain. Neuroimaging is crucial for the diagnosis and management of a number of inherited metabolic disorders. Among these, inherited white-matter disorders commonly affect both the nervous system and endocrine organs. Magnetic resonance imaging (MRI) has enabled new classifications of these disorders that have greatly enhanced both our diagnostic ability and our understanding of these complex disorders. Beyond the classic leukodystrophies, we are increasingly recognizing new hereditary leukoencephalopathies such as the hypomyelinating disorders. Conventional imaging can be unrevealing in some metabolic disorders, but proton magnetic resonance spectroscopy (MRS) may be able to directly visualize the metabolic abnormality in certain disorders. Hence, neuroimaging can enhance our understanding of pathogenesis, even in the absence of a pathologic specimen. This review aims to present pathognomonic brain MRI lesion patterns, the diagnostic capacity of proton MRS, and information from clinical and laboratory testing that can aid diagnosis. We demonstrate that applying an advanced neuroimaging approach enhances current diagnostics and management. Additional information on inherited and metabolic disorders of the brain can be found in Chapter 63 in the second volume of this series.

  16. Functionalization of PEGylated Fe3O4 magnetic nanoparticles with tetraphosphonate cavitand for biomedical application

    NASA Astrophysics Data System (ADS)

    Tudisco, C.; Bertani, F.; Cambria, M. T.; Sinatra, F.; Fantechi, E.; Innocenti, C.; Sangregorio, C.; Dalcanale, E.; Condorelli, G. G.

    2013-11-01

    In this contribution, Fe3O4 magnetic nanoparticles (MNPs) have been functionalized with a tetraphosphonate cavitand receptor (Tiiii), capable of complexing N-monomethylated species with high selectivity, and polyethylene glycol (PEG) via click-chemistry. The grafting process is based on MNP pre-functionalization with a bifunctional phosphonic linker, 10-undecynylphosphonic acid, anchored on an iron surface through the phosphonic group. The Tiiii cavitand and the PEG modified with azide moieties have then been bonded to the resulting alkyne-functionalized MNPs through a ``click'' reaction. Each reaction step has been monitored by using X-ray photoelectron and FTIR spectroscopies. PEG and Tiiii functionalized MNPs have been able to load N-methyl ammonium salts such as the antitumor drug procarbazine hydrochloride and the neurotransmitter epinephrine hydrochloride and release them as free bases. In addition, the introduction of PEG moieties promoted biocompatibility of functionalized MNPs, thus allowing their use in biological environments.

  17. Nature versus nurture: Functional assessment of restoration effects on wetland services using Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sundareshwar, P. V.; Richardson, C. J.; Gleason, Robert A.; Pellechia, Perry J.; Honomichl, Shawn

    2009-02-01

    Land-use change has altered the ability of wetlands to provide vital services such as nutrient retention. While compensatory practices attempt to restore degraded wetlands and their functions, it is difficult to evaluate the recovery of soil biogeochemical functions that are critical for restoration of ecosystem services. Using solution 31P Nuclear Magnetic Resonance Spectroscopy, we examined the chemical forms of phosphorus (P) in soils from wetlands located across a land-use gradient. We report that soil P diversity, a functional attribute, was lowest in farmland, and greatest in native wetlands. Soil P diversity increased with age of restoration, indicating restoration of biogeochemical function. The trend in soil P diversity was similar to documented trends in soil bacterial taxonomic composition but opposite that of soil bacterial diversity at our study sites. These findings provide insights into links between ecosystem structure and function and provide a tool for evaluating the success of ecosystem restoration efforts.

  18. Nature versus nurture: functional assessment of restoration effects on wetland services using Nuclear Magnetic Resonance Spectroscopy

    USGS Publications Warehouse

    Sundareshwar, P.V.; Richardson, C.J.; Gleason, R.A.; Pellechia, P.J.; Honomichl, S.

    2009-01-01

    Land-use change has altered the ability of wetlands to provide vital services such as nutrient retention. While compensatory practices attempt to restore degraded wetlands and their functions, it is difficult to evaluate the recovery of soil biogeochemical functions that are critical for restoration of ecosystem services. Using solution 31P Nuclear Magnetic Resonance Spectroscopy, we examined the chemical forms of phosphorus (P) in soils from wetlands located across a land-use gradient. We report that soil P diversity, a functional attribute, was lowest in farmland, and greatest in native wetlands. Soil P diversity increased with age of restoration, indicating restoration of biogeochemical function. The trend in soil P diversity was similar to documented trends in soil bacterial taxonomic composition but opposite that of soil bacterial diversity at our study sites. These findings provide insights into links between ecosystem structure and function and provide a tool for evaluating the success of ecosystem restoration efforts. Copyright 2009 by the American Geophysical Union.

  19. Determination of the Time-Space Magnetic Correlation Functions in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Weygand, J. M.; Matthaeus, W. H.; Kivelson, M.; Dasso, S.

    2013-12-01

    Magnetic field data from many different intervals and 7 different solar wind spacecraft are employed to estimate the scale-dependent time decorrelation function in the interplanetary magnetic field in both the slow and fast solar wind. This estimation requires correlations varying with both space and time lags. The two point correlation function with no time lag is determined by correlating time series data from multiple spacecraft separated in space and for complete coverage of length scales relies on many intervals with different spacecraft spatial separations. In addition we employ single spacecraft time-lagged correlations, and two spacecraft time lagged correlations to access different spatial and temporal correlation data. Combining these data sets gives estimates of the scale-dependent time decorrelation function, which in principle tells us how rapidly time decorrelation occurs at a given wavelength. For static fields the scale-dependent time decorrelation function is trivially unity, but in turbulence the nonlinear cascade process induces time-decorrelation at a given length scale that occurs more rapidly with decreasing scale. The scale-dependent time decorrelation function is valuable input to theories as well as various applications such as scattering, transport, and study of predictability. It is also a fundamental element of formal turbulence theory. Our results are extension of the Eulerian correlation functions estimated in Matthaeus et al. [2010], Weygand et al [2012; 2013].

  20. Multimodal imaging guided photothermal therapy using functionalized graphene nanosheets anchored with magnetic nanoparticles.

    PubMed

    Yang, Kai; Hu, Lilei; Ma, Xingxing; Ye, Shuoqi; Cheng, Liang; Shi, Xiaoze; Li, Changhui; Li, Yonggang; Liu, Zhuang

    2012-04-10

    In this work, a nanoscale reduced graphene oxide-iron oxide nanoparticle (RGO-IONP) complex is noncovalently functionalized with polyethylene glycol (PEG), obtaining a RGO-IONP-PEG nanocomposite with excellent physiological stability, strong NIR optical absorbance, and superparamagnetic properties. Using this theranostic nanoprobe, in-vivo triple modal fluorescence, photoacoustic, and magnetic resonance imaging are carried out, uncovering high passive tumor targeting, which is further used for effective photothermal ablation of tumors in mice.

  1. Direct electrochemistry and electrocatalysis of lobetyolin via magnetic functionalized reduced graphene oxide film fabricated electrochemical sensor.

    PubMed

    Sun, Bolu; Gou, Xiaodan; Bai, Ruibin; Abdelmoaty, Ahmed Attia Ahmed; Ma, Yuling; Zheng, Xiaoping; Hu, Fangdi

    2017-05-01

    A novel lobetyolin electrochemical sensor based on a magnetic functionalized reduced graphene oxide/Nafion nanohybrid film has been introduced in this work. The magnetic functionalized reduced graphene oxide was characterized by fourier transform infrared spectroscopy, atomic force microscope, X-ray diffraction, transmission electron microscopy and thermogravimetric analysis. The scanning electron microscopy characterized the morphology and microstructure of the prepared sensors, and the electrochemical effective surface areas of the prepared sensors were also calculated by chronocoulometry method. The electrochemical behavior of lobetyolin on the magnetic functionalized reduced graphene oxide/Nafion nanohybrid modified glassy carbon electrode was investigated by cyclic voltammetry and differential pulse voltammetry in a phosphate buffer solution of pH6.0. The electron-transfer coefficient (α), electron transfer number (n), and electrode reaction rate constant (Κs) were calculated as 0.78, 0.73, and 4.63s(-1), respectively. Under the optimized conditions, the sensor based on magnetic functionalized reduced graphene oxide/Nafion showed a linear voltammetric response to the lobetyolin concentration at 1.0×10(-7) to 1.0×10(-4)mol/L with detection limit (S/N=3)of 4.3×10(-8)mol/L. The proposed sensor also displayed acceptable reproducibility, long-term stability, and high selectivity, and performs well for analysis of lobetyolin in real samples. The voltammetric sensor was successfully applied to detect lobetyolin in Codonopsis pilosula with recovery values in the range of 96.12%-102.66%.

  2. Functional magnetic resonance imaging before and after ventriculoperitoneal shunting for hydrocephalus--case report.

    PubMed

    Fukuhara, T; Luciano, M G; Liu, J Z; Yue, G H

    2001-12-01

    A 70-year-old man with hydrocephalus was examined with functional magnetic resonance (fMR) imaging before and after ventriculoperitoneal shunting. Preoperatively, activation by right hand exercise revealed only a slight signal increase in the peri-rolandic area. However, 3 months after ventriculoperitoneal shunting, a significant signal increase was observed. fMR imaging may detect activity-related improvement of cerebral blood flow responses in patients with hydrocephalus after surgical treatment.

  3. Hospital-acquired thrombocytopenia.

    PubMed

    McMahon, Christine M; Cuker, Adam

    2014-10-01

    The development of thrombocytopenia is common in hospitalized patients and is associated with increased mortality. Frequent and important causes of thrombocytopenia in hospitalized patients include etiologies related to the underlying illness for which the patient is admitted, such as infection and disseminated intravascular coagulation, and iatrogenic etiologies such as drug-induced immune thrombocytopenia, heparin-induced thrombocytopenia, posttransfusion purpura, hemodilution, major surgery, and extracorporeal circuitry. This review presents a brief discussion of the pathophysiology, distinguishing clinical features, and management of these etiologies, and provides a diagnostic approach to hospital-acquired thrombocytopenia that considers the timing and severity of the platelet count fall, the presence of hemorrhage or thrombosis, the clinical context, and the peripheral blood smear. This approach may offer guidance to clinicians in distinguishing among the various causes of hospital-acquired thrombocytopenia and providing management appropriate to the etiology.

  4. Dynamic response functions and helical gaps in interacting Rashba nanowires with and without magnetic fields

    NASA Astrophysics Data System (ADS)

    Pedder, Christopher J.; Meng, Tobias; Tiwari, Rakesh P.; Schmidt, Thomas L.

    2016-12-01

    A partially gapped spectrum due to the application of a magnetic field is one of the main probes of Rashba spin-orbit coupling in nanowires. Such a "helical gap" manifests itself in the linear conductance, as well as in dynamic response functions such as the spectral function, the structure factor, or the tunneling density of states. In this paper we investigate theoretically the signature of the helical gap in these observables with a particular focus on the interplay between Rashba spin-orbit coupling and electron-electron interactions. We show that in a quasi-one-dimensional wire, interactions can open a helical gap even without magnetic field. We calculate the dynamic response functions using bosonization, a renormalization group analysis, and the exact form factors of the emerging sine-Gordon model. For special interaction strengths, we verify our results by re-fermionization. We show how the two types of helical gaps, caused by magnetic fields or interactions, can be distinguished in experiments.

  5. ZrO2-functionalized magnetic mesoporous SiO2 as effective phosphate adsorbent.

    PubMed

    Wang, Wenjuan; Zhou, Juan; Wei, Dan; Wan, Haiqin; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

    2013-10-01

    Phosphate pollution may cause eutrophication of the aquatic environment. In the present study, magnetic mesoporous SiO2 (denoted as MMS) and ZrO2-functionalized magnetic mesoporous SiO2 (denoted as ZrO2-MMS) were prepared and phosphate adsorption over the materials was investigated. The adsorbents were characterized by X-ray diffraction, transition electron microscopy, vibration sample magnetometer, N2 adsorption/desorption, zeta-potential measurement, and X-ray photoelectron spectroscopy. The results showed that MMS consisted of magnetite with particle sizes of 10-20 nm and ordered mesoporous SiO2 with the most probable pore diameter of 2.0 nm. The adsorbents could be readily separated and recovered under external magnetic field. The surface grafting of ZrO2 onto MMS led to an increase in surface zeta potential due to the formation of covalently linked ZrO2 functionality on the surface of MMS. Moreover, ZrO2 functionalization resulted in enhanced phosphate adsorption. Phosphate adsorption isotherms over the adsorbents could be well described by the Freundlich model. Phosphate adsorption kinetics followed the pseudo-second-order kinetics and the adsorption rate decreased with initial phosphate concentration. Additionally, increasing pH led to suppressed phosphate adsorption, and phosphate adsorption slightly increased with ionic strength.

  6. Wave function properties of a single and a system of magnetic flux tube(s) oscillations

    NASA Astrophysics Data System (ADS)

    Esmaeili, Shahriar; Nasiri, Mojtaba; Dadashi, Neda; Safari, Hossein

    2016-10-01

    In this study, the properties of wave functions of the MHD oscillations for a single and a system of straight flux tubes are investigated. Magnetic flux tubes with a straight magnetic field and longitudinal density stratification were considered in zero-β approximation. A single three-dimensional wave equation (eigenvalue problem) is solved for longitudinal component of the perturbed magnetic field using the finite element method. Wave functions (eigenfunction of wave equation) of the MHD oscillations are categorized into sausage, kink, helical kink, and fluting modes. Exact recognition of the wave functions and the frequencies of oscillations can be used in coronal seismology and also helps to the future high-resolution instruments that would be designed for studying the properties of the solar loop oscillations in details. The properties of collective oscillations of nonidentical and identical system of flux tubes and their interactions are studied. The ratios of frequencies, the oscillation frequencies of a system of flux tubes to their equivalent monolithic tube (ω sys/ω mono), are obtained between 0.748 and 0.841 for a system of nonidentical tubes, whereas the related ratios of frequencies for a system of identical flux tubes are fluctuated around 0.761.

  7. Functional alterations in immature cultured rat hippocampal neurons after sustained exposure to static magnetic fields.

    PubMed

    Hirai, Takao; Yoneda, Yukio

    2004-01-15

    In cultured rat hippocampal neurons, gradual increases were seen in the expression of microtubule-associated protein-2 (MAP-2), neuronal nuclei (NeuN) and growth-associated protein-43 (GAP-43), in proportion to increased duration, up to 9 days in vitro (DIV). Sustained exposure to static magnetic fields at 100 mT for up to 9 DIV significantly decreased expression of MAP-2 and NeuN in cultured rat hippocampal neurons without markedly affecting GAP-43 expression. Although a significant increase was seen in the expression of glial fibrillary acidic protein (GFAP) in hippocampal neuronal preparations cultured for 6-9 DIV under sustained magnetism, GFAP and proliferating cell nuclear antigen expression were not affected markedly in cultured astrocytes prepared from rat hippocampus and neocortex, irrespective of cellular maturity. No significant alteration was seen in cell survivability of hippocampal neurons or astrocytes cultured under sustained magnetism. In hippocampal neurons cultured for 3 DIV under sustained magnetism, marked mRNA expression was seen for N-methyl-D-aspartate (NMDA) receptor subunits, NR1, NR2A-2C, NR2D, and NR3A. In addition, significant potentiation of the ability of NMDA to increase intracellular free Ca(2+) ions was observed. Differential display analysis revealed a significant decrease in mRNA expression for the transcription factor ALF1 in response to sustained magnetism for 3 DIV. These results suggest that sustained exposure to static magnetic fields may affect cellular functionality and maturity in immature cultured rat hippocampal neurons through modulation of expression of particular NMDA receptor subunits.

  8. Magnetism in undoped ZnS studied from density functional theory

    SciTech Connect

    Xiao, Wen-Zhi E-mail: llwang@hun.edu.cn; Rong, Qing-Yan; Xiao, Gang; Wang, Ling-ling E-mail: llwang@hun.edu.cn; Meng, Bo

    2014-06-07

    The magnetic property induced by the native defects in ZnS bulk, thin film, and quantum dots are investigated comprehensively based on density functional theory within the generalized gradient approximation + Hubbard U (GGA + U) approach. We find the origin of magnetism is closely related to the introduction of hole into ZnS systems. The relative localization of S-3p orbitals is another key to resulting in unpaired p-electron, due to Hund's rule. For almost all the ZnS systems under study, the magnetic moment arises from the S-dangling bonds generated by Zn vacancies. The charge-neutral Zn vacancy, Zn vacancy in 1− charge sate, and S vacancy in the 1+ charge sate produce a local magnetic moment of 2.0, 1.0, and 1.0 μ{sub B}, respectively. The Zn vacancy in the neutral and 1− charge sates are the important cause for the ferromagnetism in ZnS bulk, with a Curie temperature (T{sub C}) above room temperature. For ZnS thin film with clean (111) surfaces, the spins on each surface are ferromagnetically coupled but antiferromagnetically coupled between two surfaces, which is attributable to the internal electric field between the two polar (111) surfaces of the thin film. Only surface Zn vacancies can yield local magnetic moment for ZnS thin film and quantum dot, which is ascribed to the surface effect. Interactions between magnetic moments on S-3p states induced by hole-doping are responsible for the ferromagnetism observed experimentally in various ZnS samples.

  9. The choice of the principle of functioning of the system of magnetic levitation for the device of high-performance testing of powder permanent magnets

    NASA Astrophysics Data System (ADS)

    Shaykhutdinov, D. V.; Gorbatenko, N. I.; Narakidze, N. D.; Vlasov, A. S.; Stetsenko, I. A.

    2017-02-01

    The present article focuses on permanent magnets quality control problems. High-performance direct-flow type systems for the mechanical engineering production processes are considered. The main lack of the existing high-performance direct-flow type systems is a completing phase of movement of a tested product when the movement is oscillatory and abrupt braking may be harmful for high fragility samples. A special system for permanent magnets control is offered. The system realizes the magnetic levitation of a test sample. Active correction of the electric current in magnetizing coils as the basic functioning principle of this system is offered. The system provides the required parameters of the movement of the test sample by using opposite connection of magnetizing coils. This new technique provides aperiodic nature of the movement and limited acceleration with saving of high accuracy and required timeframe of the installation in the measuring position.

  10. Arrangement for measuring the field angle of a magnetic field as a function of axial position within a magnet bore tube

    DOEpatents

    Pidcoe, Stephen V.; Zink, Roger A.; Boroski, William N.; McCaw, William R.

    1993-01-01

    An arrangement for measuring the field angle of a magnetic field as a function of axial position within a magnet bore tube of a magnet such as is used with the Superconducting Super Collider (SSC). The arrangement includes a magnetic field alignment gauge that is carried through the magnet bore tube by a positioning shuttle in predetermined increments. The positioning shuttle includes an extensible body assembly which is actuated by an internal piston arrangement. A pair of spaced inflatable cuffs are carried by the body assembly and are selectively actuated in cooperation with pressurizing of the piston to selectively drive the positioning shuttle in an axial direction. Control of the shuttle is provided by programmed electronic computer means located exteriorly of the bore tube and which controls valves provided pressurized fluid to the inflatable cuss and the piston arrangement.

  11. Advanced magnetic resonance neuroimaging of language function recovery after aphasic stroke: a technical review.

    PubMed

    Smits, Marion; Visch-Brink, Evy G; van de Sandt-Koenderman, Mieke E; van der Lugt, Aad

    2012-01-01

    Two advanced magnetic resonance neuroimaging techniques, functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), have recently made their way into clinically oriented research and hold great promise to study the brain's adaptive changes of function and structure after aphasic stroke, respectively. Such functional and structural neuroplasticity is thought to underlie the recovery of language function, occurring spontaneously and/or in the context of therapeutic intervention. With fMRI, brain activity can be visualized. Spontaneous brain activity, present in multiple brain networks, is measured with resting-state fMRI and language-related brain activity by having the subject perform a language task during scanning (task-based fMRI). With DTI the major white matter tracts, such as the dorsal and ventral language pathways and the commissural fibers, can be visualized and quantified. Both techniques are entirely noninvasive and thus offer the unique opportunity to perform multiple assessments within the same subject. To gain more insight in functional and structural neuroplasticity after aphasic stroke, advanced magnetic resonance neuroimaging studies in specific patient populations, at several stages after stroke and in the course of language recovery, are needed. Such studies will help to clarify the influence of the many factors that play a role in the recovery of language function and are thus vital to further the development of aphasia therapy. Application of these techniques in aphasic stroke patients, however, is not without challenge. The purpose of this article is to discuss the methodologic challenges of fMRI and DTI in the assessment of language recovery after aphasic stroke.

  12. Functional magnetic resonance evidence of cortical alterations in a case of reversible congenital lymphedema of the lower limb: a pilot study.

    PubMed

    Pardini, M; Bonzano, L; Roccatagliata, L; Boccardo, F; Mancardi, G; Campisi, C

    2007-03-01

    We report the first application of brain functional Magnetic Resonance Imaging (fMRI) to congenital peripheral lymphedema patients before and after microsurgical treatment. Our aim was to evaluate the effects of limb shape change on cortical organization of the motor system and how the cortical sensorimotor network restructures after microsurgical therapy. We acquired fMRI during active motor and motor imagery tasks before surgery and six months after surgery in a patient with congenital lymphedema of the left leg. fMRI data revealed activation differences in primary and secondary motor areas between the two scanning sessions for both tasks and also between the patient's and a healthy volunteer's activations. We suggest that these alterations could be related to changes in body schema representation due to the congenital lymphedema.

  13. Optimizing the function of upstanding activities in adult patients with acquired lesions of the central nervous system by using the Bobath concept approach - A case report.

    PubMed

    Jelica, Stjepan; Seper, Vesna; Davidović, Erna; Bujisić, Gordana

    2011-01-01

    Nonspecific medical gymnastic therapy may help patients after stroke achieve certain results in terms of efficiency but not in terms of quality of movement. The goal of treatment by Bobath concept is development of movement (effectiveness) and optimization of movement (efficiency). This article presents the case of a 62-year old patient who had experienced a stroke and has difficulties with standing up activities. It underscores the importance of not only recovery of function but also optimization of the function in such patients.

  14. Network asymmetry of motor areas revealed by resting-state functional magnetic resonance imaging.

    PubMed

    Yan, Li-Rong; Wu, Yi-Bo; Hu, De-Wen; Qin, Shang-Zhen; Xu, Guo-Zheng; Zeng, Xiao-Hua; Song, Hua

    2012-02-01

    There are ample functional magnetic resonance imaging (fMRI) studies on functional brain asymmetries, and the asymmetry of cerebral network in the resting state may be crucial to brain function organization. In this paper, a unified schema of voxel-wise functional connectivity and asymmetry analysis was presented and the network asymmetry of motor areas was studied. Twelve healthy male subjects with mean age 29.8 ± 6.4 were studied. Functional network in the resting state was described by using functional connectivity magnetic resonance imaging (fcMRI) analysis. Motor areas were selected as regions of interest (ROIs). Network asymmetry, including intra- and inter-network asymmetries, was formulated and analyzed. The intra-network asymmetry was defined as the difference between the left and right part of a particular functional network. The inter-network asymmetry was defined as the difference between the networks for a specific ROI in the left hemisphere and its homotopic ROI in the right hemisphere. Primary motor area (M1), primary sensory area (S1) and premotor area (PMA) exhibited higher functional correlation with the right parietal-temporal-occipital circuit and the middle frontal gyrus than they did with the left hemisphere. Right S1 and right PMA exhibited higher functional correlation with the ipsilateral precentral and supramarginal areas. There exist the large-scale hierarchical network asymmetries of the motor areas in the resting state. These asymmetries imply the right hemisphere dominance for predictive motor coding based on spatial attention and higher sensory processing load for the motor performance of non-dominant hemisphere.

  15. Magnetic stimulation for the measurement of respiratory and skeletal muscle function.

    PubMed

    Man, W D-C; Moxham, J; Polkey, M I

    2004-11-01

    Respiratory and skeletal muscle function is of interest in many areas of pulmonary and critical care medicine. The capacity of the respiratory muscle pump to respond to the load imposed by disease is the basis of an understanding of ventilatory failure. Over the last four decades, considerable progress has been made in quantifying the capacity of the respiratory muscles, in terms of strength, endurance and fatigue. With the development of magnetic stimulation, it has recently become possible to nonvolitionally assess the respiratory muscles in a clinically acceptable way. This is of particular interest in the investigation of patients receiving critical care, those with neuromuscular disease, and in children where volitional efforts are either not possible or likely to be sub-maximal. Furthermore, the adaptation of these techniques to quantify the strength of peripheral muscles, such as the quadriceps, has allowed the effects of muscle training or rehabilitation, uninfluenced by learning effect, to be assessed. This article focuses on the physiological basis of magnetic nerve stimulation, and reviews how the technique has been applied to measure muscle strength and fatigue, with particular emphasis upon the diaphragm. The translation of magnetic stimulation into a clinical tool is described, and how it may be of diagnostic, prognostic and therapeutic value in several areas of pulmonary medicine. In particular, the use of magnetic stimulation in neuromuscular disease, the intensive care setting, chronic obstructive pulmonary disease and paediatrics will be discussed.

  16. Functional dynamics of hippocampal glutamate during associative learning assessed with in vivo (1)H functional magnetic resonance spectroscopy.

    PubMed

    Stanley, Jeffrey A; Burgess, Ashley; Khatib, Dalal; Ramaseshan, Karthik; Arshad, Muzamil; Wu, Helen; Diwadkar, Vaibhav A

    2017-03-29

    fMRI has provided vibrant characterization of regional and network responses associated with associative learning and memory; however, their relationship to functional neurochemistry is unclear. Here, we introduce a novel application of in vivo proton functional magnetic resonance spectroscopy ((1)H fMRS) to investigate the dynamics of hippocampal glutamate during paired-associated learning and memory in healthy young adults. We show that the temporal dynamics of glutamate differed significantly during processes of memory consolidation and retrieval. Moreover, learning proficiency was predictive of the temporal dynamics of glutamate such that fast learners were characterized by a significant increase in glutamate levels early in learning, whereas this increase was only observed later in slow learners. The observed functional dynamics of glutamate provides a novel in vivo marker of brain function. Previously demonstrated N-methyl-D-aspartate (NMDA) receptor mediated synaptic plasticity during associative memory formation may be expressed in glutamate dynamics, which the novel application of (1)H MRS is sensitive to. The novel application of (1)H fMRS can provide highly innovative vistas for characterizing brain function in vivo, with significant implications for studying glutamatergic neurotransmission in health and disorders such as schizophrenia.

  17. Aberrant regional neural fluctuations and functional connectivity in generalized anxiety disorder revealed by resting-state functional magnetic resonance imaging.

    PubMed

    Wang, Wei; Hou, Jingming; Qian, Shaowen; Liu, Kai; Li, Bo; Li, Min; Peng, Zhaohui; Xin, Kuolin; Sun, Gang

    2016-06-15

    The purpose of this study was to investigate the neural activity and functional connectivity in generalized anxiety disorder (GAD) during resting state, and how these alterations correlate to patients' symptoms. Twenty-eight GAD patients and 28 matched healthy controls underwent resting-state functional magnetic resonance (fMRI) scans. Amplitude of low-frequency fluctuation (ALFF) and seed-based resting-state functional connectivity (RSFC) were computed to explore regional activity and functional integration, and were compared between the two groups using the voxel-based two-sample t test. Pearson's correlation analyses were performed to examine the neural relationships with demographics and clinical symptoms scores. Compared to controls, GAD patients showed functional abnormalities: higher ALFF in the bilateral dorsomedial prefrontal cortex, bilateral dorsolateral prefrontal cortex and left precuneus/posterior cingulate cortex; lower connectivity in prefrontal gyrus; lower in prefrontal-limbic and cingulate RSFC and higher prefrontal-hippocampus RSFC were correlated with clinical symptoms severity, but these associations were unable to withstand correction for multiple testing. These findings may help facilitate further understanding of the potential neural substrate of GAD.

  18. A New Adaptive Diffusive Function for Magnetic Resonance Imaging Denoising Based on Pixel Similarity

    PubMed Central

    Heydari, Mostafa; Karami, Mohammad Reza

    2015-01-01

    Although there are many methods for image denoising, but partial differential equation (PDE) based denoising attracted much attention in the field of medical image processing such as magnetic resonance imaging (MRI). The main advantage of PDE-based denoising approach is laid in its ability to smooth image in a nonlinear way, which effectively removes the noise, as well as preserving edge through anisotropic diffusion controlled by the diffusive function. This function was first introduced by Perona and Malik (P-M) in their model. They proposed two functions that are most frequently used in PDE-based methods. Since these functions consider only the gradient information of a diffused pixel, they cannot remove noise in noisy images with low signal-to-noise (SNR). In this paper we propose a modified diffusive function with fractional power that is based on pixel similarity to improve P-M model for low SNR. We also will show that our proposed function will stabilize the P-M method. As experimental results show, our proposed function that is modified version of P-M function effectively improves the SNR and preserves edges more than P-M functions in low SNR. PMID:26955563

  19. Written discourse and acquired brain impairment: evaluation of structural and semantic features of personal letters from a Systemic Functional Linguistic perspective.

    PubMed

    Mortensen, Lynne

    2005-01-01

    This qualitative study investigated written discourse in the form of personal letters written by ten people with aphasia following stroke and ten people with cognitive-language disorder as a consequence of traumatic brain injury, and compared their performance with 15 non brain-damaged writers. Personal letters perform the dual function of providing information and maintaining social relationships. Using the Systemic Functional Linguistics framework for investigation, letters were examined in terms of their dual functions, and at two different strata of language--generic structure and semantic organisation. A small quantum of research suggests that the dissociation between different strata of language (i.e., macro and micro linguistic abilities), identified in the spoken discourse of people with aphasia and people with cognitive-language disorder is mirrored in written discourse. Aphasic writers largely maintain coherent text structure while writers with cognitive-language impairment demonstrate problems with global text coherence and the episodic structure of texts. Results of the generic structure analysis did not support the hypothesis. However, the semantic Move analysis revealed how diminished linguistic resources, most evident in the letters written by the subjects with aphasia, impacted upon the semantic diversity of the text, as well as the interpersonal function of the personal letter. Variable performance as a feature pathology and normality is highlighted and clinical implications discussed.

  20. Written Discourse and Acquired Brain Impairment: Evaluation of Structural and Semantic Features of Personal Letters from a Systemic Functional Linguistic Perspective

    ERIC Educational Resources Information Center

    Mortensen, Lynne

    2005-01-01

    This qualitative study investigated written discourse in the form of personal letters written by ten people with aphasia following stroke and ten people with cognitive-language disorder as a consequence of traumatic brain injury, and compared their performance with 15 non brain-damaged writers. Personal letters perform the dual function of…

  1. Exact transfer functions for the PEP storage ring magnets and some general characteristics and techniques

    SciTech Connect

    Spencer, J.E.

    1982-05-01

    The exact, ion-optical transfer functions for the dipoles, quadrupoles and sextupoles of the PEP standard PODC cell are calculated for any single particle with initial coordinates (r, p, s). Modifications resulting from radiative energy loss are also calculated and discussed. These functions allow one to characterize individual magnets or classes of magnets by their aberrations and thereby simplify their study and correction. In contrast to high-energy spectrometers where aberrations are often analyzed away, those in storage rings drive series of high order resonances, even for perfect magnets (2), that can produce stop bands and other effects which can seriously limit performance. Thus, one would like to eliminate them altogether or failing this to develop local and global correction schemes. Even then, one should expect higher order effects to influence injection, extraction or single-pass systems either because of orbit distortions or overly large phase spece distortions such as may occur in low-beta insertions or any final-focus optics. The term exact means that the results here are based on solving the relativistic Lorentz force equation with accurate representations of measured magnetostatic fields. Such fields satisfy Maxwell's equations and are the actual fields seen by a particle as it propagates around a real storage ring. This is discussed in detail and illustrated with examples that show that this is possible, practical and may even be useful.

  2. Recent advances in surface chemistry strategies for the fabrication of functional iron oxide based magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Turcheniuk, Kostiantyn; Tarasevych, Arkadii V.; Kukhar, Valeriy P.; Boukherroub, Rabah; Szunerits, Sabine

    2013-10-01

    The synthesis of superparamagnetic nanostructures, especially iron-oxide based nanoparticles (IONPs), with appropriate surface functional groups has been intensively researched for many high-technological applications, including high density data storage, biosensing and biomedicine. In medicine, IONPs are nowadays widely used as contrast agents for magnetic resonance imaging (MRI), in hyperthermia therapy, but are also exploited for drug and gene delivery, detoxification of biological fluids or immunoassays, as they are relatively non-toxic. The use of magnetic particles in vivo requires IONPs to have high magnetization values, diameters below 100 nm with overall narrow size distribution and long time stability in biological fluids. Due to the high surface energies of IONPs agglomeration over time is often encountered. It is thus of prime importance to modify their surface to prevent aggregation and to limit non-specific adsorption of biomolecules onto their surface. Such chemical modifications result in IONPs being well-dispersed and biocompatible, and allow for targeted delivery and specific interactions. The chemical nature of IONPs thus determines not only the overall size of the colloid, but also plays a significant role for in vivo and in vitro applications. This review discusses the different concepts currently used for the surface functionalization and coating of iron oxide nanoparticles. The diverse strategies for the covalent linking of drugs, proteins, enzymes, antibodies, and nucleotides will be discussed and the chemically relevant steps will be explained in detail.

  3. An engineered glove for investigating the neural correlates of finger movements using functional magnetic resonance imaging

    PubMed Central

    Bonzano, Laura; Tacchino, Andrea; Roccatagliata, Luca; Inglese, Matilde; Mancardi, Giovanni Luigi; Novellino, Antonio; Bove, Marco

    2015-01-01

    Objective measurement of concomitant finger motor performance is recommended for functional magnetic resonance imaging (fMRI) studies investigating brain activity during finger tapping tasks, because performance modality and ability can influence the selection of different neural networks. In this study, we present a novel glove system for quantitative evaluation of finger opposition movements during fMRI (called Glove Analyzer for fMRI, GAF). Several tests for magnetic resonance (MR) compatibility were performed concerning magnet forces, image artifacts and right functioning of the system. Then, pilot fMRI of finger opposition tasks were conducted at 1.5T and 3T to investigate the neural correlates of sequences of finger opposition movements with the right hand, with simultaneous behavioral recording by means of GAF. All the MR compatibility tests succeeded, and the fMRI analysis revealed mainly the activation of the left sensorimotor areas and right cerebellum, regions that are known to be involved in finger movements. No artifactual clusters were detected in the activation maps. At the same time, through the parameters calculated by GAF it was possible to describe the sensorimotor strategy adopted by the subjects during the required task. Thus, the proposed device resulted to be MR compatible and can be useful for future fMRI studies investigating the neural correlates of finger opposition movements, allowing follow-up studies and comparisons among different groups of patients. PMID:26441600

  4. Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis.

    PubMed

    Yang, Hee-Man; Choi, Hye Min; Jang, Sung-Chan; Han, Myeong Jin; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

    2015-10-01

    Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes.

  5. Highly Stable Amine Functionalized Iron Oxide Nanoparticles Designed for Magnetic Particle Imaging (MPI)

    PubMed Central

    Arami, Hamed; Krishnan, Kannan M.

    2014-01-01

    Magnetic particle imaging (MPI) is a promising medical imaging technology that uses iron oxide nanoparticles (NPs) as clinically safe tracers. The core and hydrodynamic size of these NPs determine the signal intensity and spatial resolution in MPI, whilst their monodispersity when preserved during the biomedical applications, generates a consistently high quality MPI image. Using an effective process to coat the synthesized NPs with amine terminated PEG molecules, we show by dynamic light scattering (DLS) that they are water-soluble with long-term stability in biological media such as phosphate buffered saline (PBS) and sodium bicarbonate buffers and Dulbecco’s modified Eagle medium (DMEM) enriched with 10% fetal bovine serum (FBS). Further, using magnetic particle spectroscopy (MPS), to measure the particle response function (PRF), defined as the derivative of the magnetization of the nanoparticles, we predict the MPI performance of these nanoparticles at a driving field frequency of 25 kHz. The MPS efficacy of the functionalized nanoparticles was also monitored over time, and both signal intensity and resolution remained unchanged even after seven days of incubation. This is attributed to the dominant contribution of the Néel relaxation mechanism of the monodisperse and highly stable nanoparticles, which was preserved through the incubation period. PMID:25554710

  6. Acquired Factor V Inhibitor

    PubMed Central

    Hirai, Daisuke; Yamashita, Yugo; Masunaga, Nobutoyo; Katsura, Toshiaki; Akao, Masaharu; Okuno, Yoshiaki; Koyama, Hiroshi

    2016-01-01

    Inhibitors directed against factor V rarely occur, and the clinical symptoms vary. We herein report the case of a patient who presented with a decreased factor V activity that had decreased to <3 %. We administered vitamin K and 6 units of fresh frozen plasma, but she thereafter developed an intracerebral hemorrhage. It is unclear whether surgery >10 years earlier might have caused the development of a factor V inhibitor. The treatment of acquired factor V inhibitors is mainly the transfusion of platelet concentrates and corticosteroids. Both early detection and the early initiation of the treatment of factor V inhibitor are thus considered to be important. PMID:27746446

  7. Electronic and magnetic properties of silicon supported organometallic molecular wires: a density functional theory (DFT) study

    NASA Astrophysics Data System (ADS)

    Liu, Xia; Tan, Yingzi; Li, Xiuling; Wu, Xiaojun; Pei, Yong

    2015-08-01

    The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to the well-studied gas phase TM-benzene molecular wires. Si-[Mn(styrene)]∞ and Si-[Cr(styrene)]∞ single molecular wires (SMWs) are a ferromagnetic semiconductor and half metal, respectively. Creation of H-atom defects on the silicon surface can introduce an impurity metallic band, which leads to novel half-metallic magnetism of a Si-[Mn(styrene)]∞ system. Moreover, double molecular wires (DMWs) containing two identical or hetero SMWs are theoretically designed. The [Mn(styrene)]∞-[Cr(styrene)]∞ DMW exhibits half-metallic magnetism where the spin-up and spin-down channels are contributed by two single molecular wires. Finally, we demonstrate that introducing a TM-defect may significantly affect the electronic structure and magnetic properties of molecular wires. These studies provide new insights into the structure and properties of surface supported 1-D sandwiched molecular wires and may inspire the future experimental synthesis of substrate confined organometallic sandwiched molecular wires.The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to

  8. [Application of pharmacologic functional magnetic resonance imaging (phMRI) in the research of affective disorders].

    PubMed

    Édes, Andrea Edit; Gonda, Xénia; Bagdy, György; Juhász, Gabriella

    2014-06-01

    Many common psychiatric disorders such as depression and anxiety disorders are associated with dysfunction in the monoamine neurotransmission in the central nervous system. However, the investigation of these pathophysiological processes in the human living brain is difficult. In case of functional magnetic resonance imaging (fMRI), a non-invasive method for the examination of brain activity, the activity-inducing stimulus is generally a cognitive psychological test, while during pharmacological magnetic resonance imaging (phMRI) the activation is triggered by a specific pharmacon. In the present work we review the available scientific literature related to this method using literature search in PubMed. Through application of a selective pharmacon like the selective serotonine reuptake inhibitors (SSRIs) citalopram or escitalopram in a challenge phMRI study, the serotonergic neurotransmitter system can be examined specifically, the functioning brain areas involved in its effect become observable.. With modulation phMRI we can monitor the long-term effect of an antidepressant or we can examine the immediate effect of a single dose of the medication on congitive psychological functions like emotional processing. Thus, the application of phMRI methods may help deepen our understanding of serotonergic function in the living human brain as well as of diseases related to serotonergic neurotransmitter system dysfunction.

  9. Correlation functions of the electric and magnetic fields in the vicinity of a metal surface

    NASA Astrophysics Data System (ADS)

    Langsjoen, Luke; Joynt, Robert; Vavilov, Maxim; Poudel, Amrit

    2012-02-01

    The Johnson noise-induced relaxation rate of a charge or spin qubit for a transition at a particular frequency in the vicinity of a metal boundary is proportional to the temporal Fourier component at that frequency of the electric or magnetic correlation function evaluated at the position of the qubit. These correlation functions are shown to be greatly enhanced compared to the blackbody result in the near vicinity of the metal due to the contribution of evanescent waves. As such, we expect a measurable enhancement of qubit decoherence due to the contribution of evanescent waves. We use a Green's dyadic approach to calculate the correlation functions of the fluctuating electric and magnetic fields in the vicinity of a conducting surface. In a local treatment of the dielectric properties of the metal this enhancement diverges as the inverse cube of the distance from the boundary, and for distances less than the order of the Fermi wavelength of the metal a nonlocal treatment is necessary to obtain an accurate result. We present a calculation of the correlation function for the full range of distances.

  10. SiN-SiC nanofilm: A nano-functional ceramic with bipolar magnetic semiconducting character

    SciTech Connect

    Zhang, Jiahui; Li, Xingxing; Yang, Jinlong

    2014-04-28

    Nowadays, functional ceramics have been largely explored for application in various fields. However, magnetic functional ceramics for spintronics remain little studied. Here, we propose a nano-functional ceramic of sphalerite SiN-SiC nanofilm with intrinsic ferromagnetic order. Based on first principles calculations, the SiN-SiC nanofilm is found to be a ferromagnetic semiconductor with an indirect band gap of 1.71 eV. By mean field theory, the Curie temperature is estimated to be 304 K, close to room temperature. Furthermore, the valence band and conduction band states of the nanofilm exhibit inverse spin-polarization around the Fermi level. Thus, the SiN-SiC nanofilm is a typical bipolar magnetic semiconductor in which completely spin-polarized currents with reversible spin polarization can be created and controlled by applying a gate voltage. Such a nano-functional ceramic provides a possible route for electrical manipulation of carrier's spin orientation.

  11. Duplex communicable implanted antenna for magnetic direct feeding method: Functional electrical stimulation

    NASA Astrophysics Data System (ADS)

    Kato, Kentaro; Matsuki, Hidetoshi; Sato, Fumihiro; Satoh, Tadakuni; Handa, Nobuyasu

    2009-04-01

    Functional electrical stimulation (FES) is the therapy used for the rehabilitation of lost movement function by applying electrical stimulation (ES) to paralyzed extremities. To realize ES, we adapted the implanted direct feeding method (DFM). In this method, small implanted stimulators are placed under the skin at a depth of 10-20 mm and stimulus energy and signals for controlling devices are applied to them by a mounted system using magnetic coupling. This method has the merits of having no percutaneous points and high-precision stimulation. However, since the mounted system and implanted elements are separated, it is necessary to add feedback information from inside the body to confirm the system operation for safety therapy or to rehabilitate motor function smoothly. Satisfying both restrictions, we propose the magnetic connective dual resonance (MCDR) antenna, which has two resonance circuits. Adding the LC serial circuit to the LC parallel circuit gives the sending function. In this paper, we report the principle of the MCDR antenna and verify its duplex communication ability through communication experiment. This antenna enables DFM of FES to rehabilitate more complex movements.

  12. A portable single-sided magnet system for remote NMR measurements of pulmonary function.

    PubMed

    Dabaghyan, Mikayel; Muradyan, Iga; Hrovat, Alan; Butler, James; Frederick, Eric; Zhou, Feng; Kyriazis, Angelos; Hardin, Charles; Patz, Samuel; Hrovat, Mirko

    2014-12-01

    In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung. In order to achieve portability, one must trade off field strength and therefore spatial resolution. We report initial measurements from a ping-pong ball size region in the lung as a function of lung volume. As expected, we measured decreased signal at larger lung volumes since lung density decreases with increasing lung volume. Using a CPMG sequence with ΔTE=3.5 ms and a 20 echo train, a signal to noise ratio ~1100 was obtained from an 8.8mT planar magnet after signal averaging for 43 s. This is the first demonstration of NMR measurements made on a human lung with a light-weight planar NMR device. We argue that very low spatial resolution measurements of different lobar lung regions will provide useful diagnostic information for clinicians treating Acute Respiratory Distress Syndrome as clinicians want to avoid ventilator pressures that cause either lung over distension (too much pressure) or lung collapse (too little pressure).

  13. Functionalization of magnetic nanoparticles with high-binding capacity for affinity separation of therapeutic proteins

    NASA Astrophysics Data System (ADS)

    Masthoff, Ingke-Christine; David, Florian; Wittmann, Christoph; Garnweitner, Georg

    2014-01-01

    Magnetic nanoparticles with immobilized metal ligands were prepared for the separation of antibody fragments. First, iron oxide nanoparticles were produced in a solvothermal synthesis using triethylene glycol as solvent and iron(III) acetylacetonate as organic precursor. Via functionalization of the particles with priorly reacted 3-glycidoxypropyltrimethoxysilane and N α, N α-bis(carboxymethyl)- l-lysine (NTA), and charging with Ni2+, magnetic affinity adsorbents were obtained. The particles were applied to separate a His-tagged antibody fragment from a heterogeneous protein mixture of a microbial cultivation supernatant. Binding properties and specificity for purification of the target product ABF D1.3 scFv were optimized regarding the GNTA concentration and were found superior as compared to commercially available systems. A molar ratio of 1:2 Fe2O3:GNTA was most beneficial for the specific purification of the antibody fragment.

  14. The effects of a pyrrolidine functional group on the magnetic properties of N@C 60

    NASA Astrophysics Data System (ADS)

    Zhang, Jinying; Morton, John J. L.; Sambrook, Mark R.; Porfyrakis, Kyriakos; Ardavan, Arzhang; Briggs, G. Andrew D.

    2006-12-01

    A new stable pyrrolidine functionalized fullerene derivative, C 69H 10N 2O 2, has been synthesized, purified by high performance liquid chromatography, and characterized by MALDI mass spectrometry, UV-vis spectroscopy, Fourier transform infrared, 1H and 13C nuclear magnetic resonance. The magnetic properties of the analogous endohedral species have been studied by both continuous wave (CW) and pulsed EPR. CW-EPR spectra indicated an anisotropic hyperfine interaction and a permanent zero-field-splitting (ZFS). Both CW and pulsed EPR showed the ZFS parameter Deff to be around 17 MHz. Pulsed EPR revealed a biexponential decay in both T 1 and T 2, yielding a molecular tumbling correlation time τc of 31.4 ± 2.5 ps.

  15. Rapid and selective separation for mixed proteins with thiol functionalized magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, Soo Youn; Ahn, Chi Young; Lee, Jiho; Lee, Jin Hyung; Chang, Jeong Ho

    2012-05-01

    Thiol group functionalized silica-coated magnetic nanoparticles (Si-MNPs@SH) were synthesized for rapid and selective magnetic field-based separation of mixed proteins. The highest adsorption efficiencies of binary proteins, bovine serum albumin (BSA; 66 kDa; p I = 4.65) and lysozyme (LYZ; 14.3 kDa; p I = 11) were shown at the pH values corresponding to their own p I in the single-component protein. In the mixed protein, however, the adsorption performance of BSA and LYZ by Si-MNPs@SH was governed not only by pH but also by the molecular weight of each protein in the mixed protein.

  16. Barkhausen spectroscopy: Non-destructive characterization of magnetic materials as a function of depth

    NASA Astrophysics Data System (ADS)

    Kypris, O.; Nlebedim, I. C.; Jiles, D. C.

    2014-05-01

    In this study, we conceptually divided a ferromagnetic specimen into layers along its depth. For each layer, we derived a non-linear integral equation that describes the attenuation with frequency and distance of magnetic Barkhausen emissions coming from that layer. We postulate that the Barkhausen spectrum measured at the surface by an induction coil can be expressed as the sum of the individual layer spectra. We show how a non-linear least squares algorithm can be used to recover the properties in individual layers. These are related to stress using an extension to the theory of ferromagnetic hysteresis. We found that the quality of the fit is influenced by the sensitivity of the ferromagnetic material to strain, as well as by the sensor-specimen coupling. The proposed method can be used for the non-destructive characterization of stress as a function of depth in magnetic materials.

  17. Electronic and magnetic properties of yttrium-doped silicon carbide nanotubes: Density functional theory investigations

    SciTech Connect

    Khaira, Jobanpreet S.; Jain, Richa N.; Chakraborty, Brahmananda; Ramaniah, Lavanya M.

    2015-06-24

    The electronic structure of yttrium-doped Silicon Carbide Nanotubes has been theoretically investigated using first principles density functional theory (DFT). Yttrium atom is bonded strongly on the surface of the nanotube with a binding energy of 2.37 eV and prefers to stay on the hollow site at a distance of around 2.25 Å from the tube. The semi-conducting nanotube with chirality (4, 4) becomes half mettalic with a magnetic moment of 1.0 µ{sub B} due to influence of Y atom on the surface. There is strong hybridization between d orbital of Y with p orbital of Si and C causing a charge transfer from d orbital of the Y atom to the tube. The Fermi level is shifted towards higher energy with finite Density of States for only upspin channel making the system half metallic and magnetic which may have application in spintronic devices.

  18. Effect of cranioplasty on functional and neuro - psychological recovery after severe acquired brain injury: fact or fake? Considerations on a single case.

    PubMed

    Corallo, Francesco; Marra, Angela; Bramanti, Placido; Calabrò, Rocco Salvatore

    2014-01-01

    Cranioplasty is performed, using autograft materials, to treat the "trephined syndrome" in patients previously submitted to craniectomy. Indeed, considerable improvements in neuropsychological deficits, control of convulsions and partial prevention of cerebral atrophy are achieved after this surgical procedure. We describe the pre- and post-operative neuropsychological and functional evaluation of a 30-year-old male patient who underwent cranioplasty following previous craniectomy for a subarachnoid hemorrhage due to a spontaneously ruptured aneurysm of the right middle cerebral artery.

  19. [Acquired coagulant factor inhibitors].

    PubMed

    Nogami, Keiji

    2015-02-01

    Acquired coagulation factor inhibitors are an autoimmune disease causing bleeding symptoms due to decreases in the corresponding factor (s) which result from the appearance of autoantibodies against coagulation factors (inhibitor). This disease is quite different from congenital coagulation factor deficiencies based on genetic abnormalities. In recent years, cases with this disease have been increasing, and most have anti-factor VIII autoantibodies. The breakdown of the immune control mechanism is speculated to cause this disease since it is common in the elderly, but the pathology and pathogenesis are presently unclear. We herein describe the pathology and pathogenesis of factor VIII and factor V inhibitors. Characterization of these inhibitors leads to further analysis of the coagulation process and the activation mechanisms of clotting factors. In the future, with the development of new clotting examination method (s), we anticipate that further novel findings will be obtained in this field through inhibitor analysis. In addition, detailed elucidation of the coagulation inhibitory mechanism possibly leading to hemostatic treatment strategies for acquired coagulation factor disorders will be developed.

  20. Neural Correlates of Symptom Dimensions in Pediatric Obsessive-Compulsive Disorder: A Functional Magnetic Resonance Imaging Study

    ERIC Educational Resources Information Center

    Gilbert, Andrew R.; Akkal, Dalila; Almeida, Jorge R. C.; Mataix-Cols, David; Kalas, Catherine; Devlin, Bernie; Birmaher, Boris; Phillips, Mary L.

    2009-01-01

    The use of functional magnetic resonance imaging on a group of pediatric subjects with obsessive compulsive disorder reveals that this group has reduced activity in neural regions underlying emotional processing, cognitive processing, and motor performance as compared to control subjects.

  1. MAGNETS

    DOEpatents

    Hofacker, H.B.

    1958-09-23

    This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.

  2. Effect of cranioplasty on functional and neuropsychological recovery after severe acquired brain injury: fact or fake? Considerations on a single case

    PubMed Central

    Corallo, Francesco; Marra, Angela; Bramanti, Placido; Calabrò, Rocco Salvatore

    2014-01-01

    Summary Cranioplasty is performed, using autograft materials, to treat the “trephined syndrome” in patients previously submitted to craniectomy. Indeed, considerable improvements in neuropsychological deficits, control of convulsions and partial prevention of cerebral atrophy are achieved after this surgical procedure. We describe the pre- and post-operative neuropsychological and functional evaluation of a 30-year-old male patient who underwent cranioplasty following previous craniectomy for a subarachnoid hemorrhage due to a spontaneously ruptured aneurysm of the right middle cerebral artery. PMID:25764258

  3. Phase transitions, magnetism and surface adsorptions assessed by meta-GGA functionals and random phase approximation

    NASA Astrophysics Data System (ADS)

    Xiao, Bing

    investigated the electronic structures and magnetism of R-VO2 using exchange-correlation functionals of all five rungs on Jacob's ladder. Our calculations show that all semilocal functionals (LSDA, GGAs and meta-GGAs) and hybrid functionals (HSE06) stabilize the spin-polarized states (ferromagnetic and anti-ferromagnetic states) over non-magentic state, which are completely opposite to experimental observation. Suprisingly, LSDA gives the best energetic descriptions for magnetic and non-magnetic phases of R-VO2 among semilocal functionals and HSE06. Othwerwise, RPA calculations are highly dependent on the inputs in the spin polarized case. With PBE inputs, RPA also fails, giving lower energies for spin-polarized states than for the non-magnetic phase. Meawhile, the results are reversed using LSDA inputs. From the computed equilibrium cell volume, we observe the error cancellation in the exchange-correlation hole of most semilocal functionals in the spin-polarized calculations. LSDA and RPA do not fit to this picture. By analyzing the local magnetic moments of vanadium atoms, it is found that the magnetic property predicted from meta-GGA can be related to its exchange enhancement factor. The physisorption of a molecule on a transition metal surface is also another difficult problem in DFT because of the long-range van der Waals interactions. The recently developed MGGA_MS family of density functionals is able to capture a portion of intermediate range dispersion interactions. Therefore, we employed MGGA_MS2 to study the physisorption of CO2 on Pt (111) surface, and the results are compared to those of PBE, PBE+D2 and optB88-vdW methods. The computed binding curves comfirm that that MGGA_MS2 indeed captures the van der Waals interactions near the equilibrium binding distance, and the obtained binding distance is also in good agreement with PBE+D2 and optB88-vdW calculations. By computing the electron density difference map (EDDM), we find that the electron densities of CO2 and

  4. Copper Ferrocyanide-Functionalized Magnetic Adsorbents Using Polyethyleneimine Coated Fe3O4 Nanoparticles for the Removal of Radioactive Cesium.

    PubMed

    Yang, Hee-Man; Hong, Sang Bum; Cho, Yong Suk; Lee, Kune-Woo; Seo, Bum-Kyoung; Moon, Jei-Kwon

    2016-03-01

    Copper ferrocyanide-functionalized magnetic nano-adsorbents were successfully synthesized by electrostatic coating of citric acid coated Fe3O4 nanoparticles with polyethyleneimine, and immobilizing copper and ferrocyanide on the surfaces of polyethyleneimine-coated nanoparticles. Radioactive cesium (Cs) adsorption tests were conducted to investigate the effectiveness of the copper ferrocyanide-functionalized magnetic nano-adsorbents toward the removal of radioactive Cs.

  5. Repetitive transcranial magnetic stimulation to improve mood and motor function in Parkinson's disease.

    PubMed

    Helmich, Rick C; Siebner, Hartwig R; Bakker, Maaike; Münchau, Alexander; Bloem, Bastiaan R

    2006-10-25

    Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that can produce lasting changes in excitability and activity in cortical regions underneath the stimulation coil (local effect), but also within functionally connected cortical or subcortical regions (remote effects). Since the clinical presentation of Parkinson's disease (PD) is related to abnormal neuronal activity within the basal ganglia and cortical regions, including the primary motor cortex, the premotor cortex and the prefrontal cortex, several studies have used rTMS to improve brain function in PD. Here, we review the studies that have investigated the possible therapeutic effects of rTMS on mood and motor function in PD patients. We highlight some methodological inconsistencies and problems, including the difficulty to define the most effective protocol for rTMS or to establish an appropriate placebo condition. We finally propose future directions of research that may help to improve the therapeutic efficacy of rTMS in PD.

  6. GPU-based parallel group ICA for functional magnetic resonance data.

    PubMed

    Jing, Yanshan; Zeng, Weiming; Wang, Nizhuan; Ren, Tianlong; Shi, Yingchao; Yin, Jun; Xu, Qi

    2015-04-01

    The goal of our study is to develop a fast parallel implementation of group independent component analysis (ICA) for functional magnetic resonance imaging (fMRI) data using graphics processing units (GPU). Though ICA has become a standard method to identify brain functional connectivity of the fMRI data, it is computationally intensive, especially has a huge cost for the group data analysis. GPU with higher parallel computation power and lower cost are used for general purpose computing, which could contribute to fMRI data analysis significantly. In this study, a parallel group ICA (PGICA) on GPU, mainly consisting of GPU-based PCA using SVD and Infomax-ICA, is presented. In comparison to the serial group ICA, the proposed method demonstrated both significant speedup with 6-11 times and comparable accuracy of functional networks in our experiments. This proposed method is expected to perform the real-time post-processing for fMRI data analysis.

  7. Design of covalently functionalized carbon nanotubes filled with metal oxide nanoparticles for imaging, therapy, and magnetic manipulation.

    PubMed

    Liu, Xiaojie; Marangon, Iris; Melinte, Georgian; Wilhelm, Claire; Ménard-Moyon, Cécilia; Pichon, Benoit P; Ersen, Ovidiu; Aubertin, Kelly; Baaziz, Walid; Pham-Huu, Cuong; Bégin-Colin, Sylvie; Bianco, Alberto; Gazeau, Florence; Bégin, Dominique

    2014-11-25

    Nanocomposites combining multiple functionalities in one single nano-object hold great promise for biomedical applications. In this work, carbon nanotubes (CNTs) were filled with ferrite nanoparticles (NPs) to develop the magnetic manipulation of the nanotubes and their theranostic applications. The challenges were both the filling of CNTs with a high amount of magnetic NPs and their functionalization to form biocompatible water suspensions. We propose here a filling process using CNTs as nanoreactors for high-yield in situ growth of ferrite NPs into the inner carbon cavity. At first, NPs were formed inside the nanotubes by thermal decomposition of an iron stearate precursor. A second filling step was then performed with iron or cobalt stearate precursors to enhance the encapsulation yield and block the formed NPs inside the tubes. Water suspensions were then obtained by addition of amino groups via the covalent functionalization of the external surface of the nanotubes. Microstructural and magnetic characterizations confirmed the confinement of NPs into the anisotropic structure of CNTs making them suitable for magnetic manipulations and MRI detection. Interactions of highly water-dispersible CNTs with tumor cells could be modulated by magnetic fields without toxicity, allowing control of their orientation within the cell and inducing submicron magnetic stirring. The magnetic properties were also used to quantify CNTs cellular uptake by measuring the cell magnetophoretic mobility. Finally, the photothermal ablation of tumor cells could be enhanced by magnetic stimulus, harnessing the hybrid properties of NP loaded-CNTs.

  8. R(∗)2 mapping for robust brain function detection in the presence of magnetic field inhomogeneity.

    PubMed

    Ngo, Giang Chau; Sutton, Bradley P

    2014-01-01

    T(*)2 mapping or R(*)2 mapping for brain function offers advantages such as providing quantitative measurements independent of the MRI acquisition parameters (e.g. echo time TE). However, magnetic field susceptibility in the human brain can prevent an accurate estimation of R(*)2, which in turn impacts the ability to study brain function. The present work investigates the effects of in-plane magnetic susceptibility-induced magnetic field gradients on R(*)2 decay. An iterative method is developed for R(*)2 estimation with an increased robustness to field inhomogeneity. The new method is further tested in a visual fMRI experiment with and without magnetic field gradients and its performance is compared to a standard BOLD fMRI and a BOLD fMRI based on echo summation. Reduced sensitivity in fMRI to in-plane magnetic gradients is obtained with the present methodology.

  9. Non-invasive mapping of calculation function by repetitive navigated transcranial magnetic stimulation.

    PubMed

    Maurer, Stefanie; Tanigawa, Noriko; Sollmann, Nico; Hauck, Theresa; Ille, Sebastian; Boeckh-Behrens, Tobias; Meyer, Bernhard; Krieg, Sandro M

    2016-11-01

    Concerning calculation function, studies have already reported on localizing computational function in patients and volunteers by functional magnetic resonance imaging and transcranial magnetic stimulation. However, the development of accurate repetitive navigated TMS (rTMS) with a considerably higher spatial resolution opens a new field in cognitive neuroscience. This study was therefore designed to evaluate the feasibility of rTMS for locating cortical calculation function in healthy volunteers, and to establish this technique for future scientific applications as well as preoperative mapping in brain tumor patients. Twenty healthy subjects underwent rTMS calculation mapping using 5 Hz/10 pulses. Fifty-two previously determined cortical spots of the whole hemispheres were stimulated on both sides. The subjects were instructed to perform the calculation task composed of 80 simple arithmetic operations while rTMS pulses were applied. The highest error rate (80 %) for all errors of all subjects was observed in the right ventral precentral gyrus. Concerning division task, a 45 % error rate was achieved in the left middle frontal gyrus. The subtraction task showed its highest error rate (40 %) in the right angular gyrus (anG). In the addition task a 35 % error rate was observed in the left anterior superior temporal gyrus. Lastly, the multiplication task induced a maximum error rate of 30 % in the left anG. rTMS seems feasible as a way to locate cortical calculation function. Besides language function, the cortical localizations are well in accordance with the current literature for other modalities or lesion studies.

  10. β-Cyclodextrin functionalized magnetic mesoporous silica colloid for cholesterol separation.

    PubMed

    Sinha, Arjyabaran; Basiruddin, Sk; Chakraborty, Atanu; Jana, Nikhil R

    2015-01-21

    Although cholesterol plays significant biochemical function in the human body, excess of it leads to various disorders, and thus, its control/separation is important in medical science and food industries. However, efficient and selective separation of cholesterol is challenging because cholesterol often exists in microheterogeneous or insoluble forms in remote organ and exists with other chemicals/biochemicals. Here, we have described a colloidal magnetic mesoporous silica (MMS)-based approach for efficient separation of cholesterol in different forms. MMS is functionalized with β-cyclodextrin for selective binding with cholesterol via host-guest interaction. The colloidal form of MMS offers effective interaction with cholesterol of any form, and magnetic property of MMS offers easier separation of bound cholesterol. Functionalized MMS is efficient in separating cholesterol crystals, water-insoluble cholesterol, and the microheterogeneous form of cholesterol from milk or a cellular environment. Developed material can be used to remove cholesterol from a complex bioenvironment and extended for large-scale cholesterol separation from food.

  11. DESIGN OF SUPERCONDUCTING COMBINED FUNCTION MAGNETS FOR THE 50 GEV PROTON BEAM LINE FOR THE J-PARC NEUTRINO EXPERIMENT.

    SciTech Connect

    WANDERER,P.; ET AL.

    2003-06-15

    Superconducting combined function magnets will be utilized for the 50GeV-750kW proton beam line for the J-PARC neutrino experiment and an R and D program has been launched at KEK. The magnet is designed to provide a combined function with a dipole field of 2.59 T and a quadrupole field of 18.7 T/m in a coil aperture of 173.4 mm. A single layer coil is proposed to reduce the fabrication cost and the coil arrangement in the 2-D cross-section results in left-right asymmetry. This paper reports the design study of the magnet.

  12. Acquired epidermodysplasia verruciformis.

    PubMed

    Rogers, Heather D; Macgregor, Jennifer L; Nord, Kristin M; Tyring, Stephen; Rady, Peter; Engler, Danielle E; Grossman, Marc E

    2009-02-01

    Epidermodysplasia verruciformis (EV) is a rare autosomal recessive genodermatosis with an increased susceptibility to specific human papillomavirus (HPV) genotypes. Classically, this viral infection leads to the development of tinea versicolor-like macules on the trunk, neck, arms, and face during childhood, and over time, these lesions can progress to squamous cell carcinoma. More recently, an EV-like syndrome has been described in patients with impaired cell-mediated immunity. We describe two cases of EV-like syndrome in HIV-positive patients, review all previously reported cases of EV in patients with impaired cell-mediated immunity, introduce the term "acquired epidermodysplasia verruciformis" to describe EV developing in the immunocompromised host and examine the limited treatment options for these patients.

  13. AIDS: acquired immunodeficiency syndrome.

    PubMed Central

    Gilmore, N. J.; Beaulieu, R.; Steben, M.; Laverdière, M.

    1983-01-01

    Acquired immunodeficiency syndrome, or AIDS, is a new illness that occurs in previously healthy individuals. It is characterized by immunodeficiency, opportunistic infections and unusual malignant diseases. Life-threatening single or multiple infections with viruses, mycobacteria, fungi or protozoa are common. A rare neoplasm, Kaposi's sarcoma, has developed in approximately one third of patients with AIDS. More than 800 cases of AIDS have been reported in North America, over 24 of them in Canada. The majority of patients are male homosexuals, although AIDS has also developed in abusers of intravenously administered drugs, Haitian immigrants, individuals with hemophilia, recipients of blood transfusions, prostitutes, and infants, spouses and partners of patients with AIDS. The cause of AIDS is unknown, but the features are consistent with an infectious process. Early diagnosis can be difficult owing to the nonspecific symptoms and signs of the infections and malignant diseases. Therefore, vigilance by physicians is of utmost importance. PMID:6342737

  14. AIDS: acquired immunodeficiency syndrome *

    PubMed Central

    Gilmore, N.J.; Beaulieu, R.; Steben, M.; Laverdière, M.

    1992-01-01

    Acquired immunodeficiency syndrome, or AIDS, is a new illness that occurs in previously healthy individuals. It is characterized by immunodeficiency, opportunistic infections and unusual malignant diseases. Life-threatening single or multiple infections with viruses, mycobacteria, fungi or protozoa are common. A rare neoplasm, Kaposi's sarcoma, has developed in approximately one third of patients with AIDS. More than 800 cases of AIDS have been reported in North America, over 24 of them in Canada. The majority of patients are male homosexuals, although AIDS has also developed in abusers of intravenously administered drugs, Haitian immigrants, individuals with hemophilia, recipients of blood transfusions, prostitutes, and infants, spouses and partners of patients with AIDS. The cause of AIDS is unknown, but the features are consistent with an infectious process. Early diagnosis can be difficult owing to the nonspecific symptoms and signs of the infections and malignant diseases. Therefore, vigilance by physicians is of the utmost importance. PMID:1544049

  15. Magnetic resonance imaging biomarkers of gastrointestinal motor function and fluid distribution

    PubMed Central

    Khalaf, Asseel; Hoad, Caroline L; Spiller, Robin C; Gowland, Penny A; Moran, Gordon W; Marciani, Luca

    2015-01-01

    Magnetic resonance imaging (MRI) is a well established technique that has revolutionized diagnostic radiology. Until recently, the impact that MRI has had in the assessment of gastrointestinal motor function and bowel fluid distribution in health and in disease has been more limited, despite the novel insights that MRI can provide along the entire gastrointestinal tract. MRI biomarkers include intestinal motility indices, small bowel water content and whole gut transit time. The present review discusses new developments and applications of MRI in the upper gastrointestinal tract, the small bowel and the colon reported in the literature in the last 5 years. PMID:26600972

  16. Functional Magnetic Resonance Imaging of Motor Cortex: Hemispheric Asymmetry and Handedness

    NASA Astrophysics Data System (ADS)

    Kim, Seong-Gi; Ashe, James; Hendrich, Kristy; Ellermann, Jutta M.; Merkle, Hellmut; Ugurbil, Kamil; Georgopoulos, Apostolos P.

    1993-07-01

    A hemispheric asymmetry in the functional activation of the human motor cortex during contralateral (C) and ipsilateral (I) finger movements, especially in right-handed subjects, was documented with nuclear magnetic resonance imaging at high field strength (4 tesla). Whereas the right motor cortex was activated mostly during contralateral finger movements in both right-handed (C/I mean area of activation = 36.8) and left-handed (C/I = 29.9) subjects, the left motor cortex was activated substantially during ipsilateral movements in left-handed subjects (C/I = 5.4) and even more so in right-handed subjects (C/I = 1.3).

  17. Vital functions of organisms in infra-low frequency magnetic fields 3. The embryogeny of mammals

    SciTech Connect

    Khizhenkov, P.K.; Bilobrov, V.M.; Zinkevich, I.I.; Zyablitsev, S.V.

    1994-10-01

    Results are presented of the experimental studies of the effect of variable (rotary) magnetic fields H at f = 6.5 Hz on the reproduction function of rats. It is shown that a pregnancy does not occur when mating takes place under the action of the field H. In the second quarter of pregnancy, the effect of the field is characterized by an increase of the mass of the body and of the internal organs of the new-born rats, among which, the growth of gemmae, spleen and of the thymus gland are particularly significant. The relative composition of the white blood cells changes as well.

  18. Cosmic-ray streaming perpendicular to the mean magnetic field. II - The gyrophase distribution function

    NASA Technical Reports Server (NTRS)

    Forman, M. A.; Jokipii, J. R.

    1978-01-01

    The distribution function of cosmic rays streaming perpendicular to the mean magnetic field in a turbulent medium is reexamined. Urch's (1977) discovery that in quasi-linear theory, the flux is due to particles at 90 deg pitch angle is discussed and shown to be consistent with previous formulations of the theory. It is pointed out that this flux of particles at 90 deg cannot be arbitrarily set equal to zero, and hence the alternative theory which proceeds from this premise is dismissed. A further, basic inconsistency in Urch's transport equation is demonstrated, and the connection between quasi-linear theory and compound diffusion is discussed.

  19. Investigating the emotional response to room acoustics: A functional magnetic resonance imaging study.

    PubMed

    Lawless, M S; Vigeant, M C

    2015-10-01

    While previous research has demonstrated the powerful influence of pleasant and unpleasant music on emotions, the present study utilizes functional magnetic resonance imaging (fMRI) to assess the positive and negative emotional responses as demonstrated in the brain when listening to music convolved with varying room acoustic conditions. During fMRI scans, subjects rated auralizations created in a simulated concert hall with varying reverberation times. The analysis detected activations in the dorsal striatum, a region associated with anticipation of reward, for two individuals for the highest rated stimulus, though no activations were found for regions associated with negative emotions in any subject.

  20. Evidence for correlations between distant intentionality and brain function in recipients: a functional magnetic resonance imaging analysis.

    PubMed

    Achterberg, Jeanne; Cooke, Karin; Richards, Todd; Standish, Leanna J; Kozak, Leila; Lake, James

    2005-12-01

    This study, using functional magnetic resonance imaging (fMRI) technology, demonstrated that distant intentionality (DI), defined as sending thoughts at a distance, is correlated with an activation of certain brain functions in the recipients. Eleven healers who espoused some form for connecting or healing at a distance were recruited from the island of Hawaii. Each healer selected a person with whom they felt a special connection as a recipient for DI. The recipient was placed in the MRI scanner and isolated from all forms of sensory contact from the healer. The healers sent forms of DI that related to their own healing practices at random 2-minute intervals that were unknown to the recipient. Significant differences between experimental (send) and control (no send) procedures were found (p = 0.000127). Areas activated during the experimental procedures included the anterior and middle cingulate area, precuneus, and frontal area. It was concluded that instructions to a healer to make an intentional connection with a sensory isolated person can be correlated to changes in brain function of that individual.

  1. Structural, electronic and magnetic effects of Al-doped niobium clusters: a density functional theory study.

    PubMed

    Wang, Huai-Qian; Li, Hui-Fang; Wang, Jia-Xian; Kuang, Xiao-Yu

    2012-07-01

    The application of the ab initio stochastic search procedure with Saunders "kick" method has been carried out for the elucidation of global minimum structures of a series of Al-doped clusters, Nb(n)Al (1 ≤ n ≤ 10). We have studied the structural characters, growth behaviors, electronic and magnetic properties of Nb(n)Al by the density functional theory calculations. Unlike the previous literature reported on Al-doped systems where ground state structures undergo a structural transition from the Al-capped frame to Al-encapsulated structure, we found that Al atom always occupies the surface of Nb(n)Al clusters and structural transition does not take place until n = 10. Note that the fragmentation proceeds preferably by the ejection of an aluminum atom other than niobium atom. According to the natural population analysis, charges always transfer from aluminum to niobium atoms. Furthermore, the magnetic moments of the Nb(n)Al clusters are mainly located on the 4d orbital of niobium atoms, and aluminum atom possesses very small magnetic moments.

  2. Density-functional study of model bidisperse ferrocolloids in an external magnetic field.

    PubMed

    Range, Gabriel M; Klapp, Sabine H L

    2005-06-08

    We present phase diagrams of a model bidisperse ferrocolloid consisting of a binary mixture of dipolar hard spheres (DHSs) under the influence of an external magnetic field. The dipole moments of the particles are chosen proportional to the particle volume to mimic real ferrocolloids, and we focus on dipole-dominated systems where isotropic attractive interactions are absent. Our results are based on density-functional theory in the modified mean-field (MMF) approximation. For one-component DHS fluids in external fields, and for corresponding mixtures dominated by one of the components, MMF theory predicts the tricritical point of the transition between an isotropic gas and a ferromagnetic liquid occurring at zero field to be changed into a critical point separating two magnetically ordered phases of different density. The corresponding critical temperature displays a nonmonotonic dependence on the field strength. Completely different behavior is found for the critical temperature related to the demixing phase transitions appearing in strongly asymmetric mixtures [G. M. Range and S. H. L. Klapp, Phys. Rev. E 70, 061407 (2004)]. For such systems, we find a monotonic decrease of the demixing critical temperature with increasing field. The field strength dependence of the critical temperature can therefore be tuned between nonmonotonic and monotonic behaviors just by changing the composition of the mixture--e.g., by adjusting the chemical potentials. This allows us to efficiently control the influence of external magnetic fields on the phase behavior over a large temperature interval.

  3. Density-functional study of model bidisperse ferrocolloids in an external magnetic field

    NASA Astrophysics Data System (ADS)

    Range, Gabriel M.; Klapp, Sabine H. L.

    2005-06-01

    We present phase diagrams of a model bidisperse ferrocolloid consisting of a binary mixture of dipolar hard spheres (DHSs) under the influence of an external magnetic field. The dipole moments of the particles are chosen proportional to the particle volume to mimic real ferrocolloids, and we focus on dipole-dominated systems where isotropic attractive interactions are absent. Our results are based on density-functional theory in the modified mean-field (MMF) approximation. For one-component DHS fluids in external fields, and for corresponding mixtures dominated by one of the components, MMF theory predicts the tricritical point of the transition between an isotropic gas and a ferromagnetic liquid occurring at zero field to be changed into a critical point separating two magnetically ordered phases of different density. The corresponding critical temperature displays a nonmonotonic dependence on the field strength. Completely different behavior is found for the critical temperature related to the demixing phase transitions appearing in strongly asymmetric mixtures [G. M. Range and S. H. L. Klapp, Phys. Rev. E 70, 061407 (2004)]. For such systems, we find a monotonic decrease of the demixing critical temperature with increasing field. The field strength dependence of the critical temperature can therefore be tuned between nonmonotonic and monotonic behaviors just by changing the composition of the mixture—e.g., by adjusting the chemical potentials. This allows us to efficiently control the influence of external magnetic fields on the phase behavior over a large temperature interval.

  4. High-capacity adsorption of dissolved hexavalent chromium using amine-functionalized magnetic corn stalk composites.

    PubMed

    Song, Wen; Gao, Baoyu; Zhang, Tengge; Xu, Xing; Huang, Xin; Yu, Huan; Yue, Qinyan

    2015-08-01

    Easily separable amine-functionalized magnetic corn stalk composites (AF-MCS) were employed for effective adsorption and reduction of toxic hexavalent chromium [Cr(VI)] to nontoxic Cr(III). The saturated magnetization of AF-MCS reached 6.2emu/g, and as a result, it could be separated from aqueous solution by a magnetic process for its superparamagnetism. The studies of various factors influencing the sorption behavior indicated that the optimum AF-MCS dosage for Cr(VI) adsorption was 1g/L, and the maximum adsorption capacity was observed at pH 3.0. The chromium adsorption perfectly fitted the Langmuir isotherm model and pseudo second order kinetic model. Furthermore, characterization of AF-MCS was investigated by means of XRD, SEM, TEM, FT-IR, BET, VSM and XPS analysis to discuss the uptake mechanism. Basically, these results demonstrated that AF-MCS prepared in this work has shown its merit in effective removal of Cr(VI) and rapid separation from effluents simultaneously.

  5. Effect of growth hormone (hGH) replacement therapy on physical work capacity and cardiac and pulmonary function in patients with hGH deficiency acquired in adulthood.

    PubMed

    Nass, R; Huber, R M; Klauss, V; Müller, O A; Schopohl, J; Strasburger, C J

    1995-02-01

    The effects of 6 months of replacement therapy with recombinant human GH (hGH) on physical work capacity and cardiac structure and function were investigated in 20 patients with hGH deficiency of adult onset in a double blind, placebo-controlled trial. The GH dose of 12.5 micrograms/kg BW was self-administered daily sc. Oxygen consumption (VO2), CO2 production, and ventilatory volumes were measured during exercise on a bicycle spiroergometer. M-Mode echocardiography was performed using standard techniques. The VO2 max data, expressed per kg BW (mL/min.kg BW) showed a significant increase from 23.2 +/- 2.4 to 30.0 +/- 2.3 (P < 0.01) in the hGH-treated group, whereas the VO2 max data, expressed per lean body mass (milliliters per min/kg lean body mass) did not change significantly in either group. Maximal O2 pulse (milliliters per beat) increased significantly from 15.2 +/- 5.6 to 19.6 +/- 3.3 mL/beat (P < 0.01), but remained constant in the placebo group. The maximal power output (watts +/- SE) increased significantly (P < 0.01) from 192.5 +/- 13.5 to 227.5 +/- 11.5 in the hGH-treated group, but remained constant in the placebo group. Cardiac structure (left ventricular posterior wall, interventricular septum thickness, left ventricular mass, left ventricular end-systolic dimension, and left ventricular end-diastolic dimension) as well as echocardiographically assessed cardiac function did not change significantly after 6 months of treatment in either group. We conclude that hGH replacement in hGH-deficient adults improves oxygen uptake and exercise capacity. These improvements in pulmonary parameters might be due to an increase in respiratory muscle strength and partly to the changes in muscle volume per se observed during hGH replacement therapy. Furthermore, an increased cardiac output might contribute to the improvement in exercise performance during hGH treatment. According to our data, hGH replacement therapy leads to an improvement of exercise capacity and

  6. Testing the Jacob's ladder of density functionals for electronic structure and magnetism of rutile VO2

    NASA Astrophysics Data System (ADS)

    Xiao, Bing; Sun, Jianwei; Ruzsinszky, Adrienn; Perdew, John P.

    2014-08-01

    We employ semilocal density functionals [local spin-density approximation (LSDA), Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA), and meta-GGAs)], LSDA plus Hubbard U (LSDA+U) theory, a nonlocal range-separated Heyd-Scuseria-Ernzerhof hybrid functional (HSE06), and the random-phase approximation (RPA) to assess their performances for the ground-state magnetism and electronic structure of a strongly correlated metal, rutile VO2. Using recent quantum Monte Carlo results as the benchmark, all tested semilocal and hybrid functionals as well as the RPA (with PBE inputs) predict the correct magnetic ground states for rutile VO2. The observed paramagnetism could arise from temperature-disordered local spin moments or from the thermal destruction of these moments. All semilocal functionals also give the correct ground-state metallicity for rutile VO2. However, in the ferromagnetic (FM) and antiferromagnetic (AFM) phases, LSDA+U and HSE06 incorrectly predict rutile VO2 to be a Mott-Hubbard insulator. For the computed electronic structures of FM and AFM phases, we find that the Tao-Perdew-Staroverov-Scuseria (TPSS) and revised TPSS (revTPSS) meta-GGAs give strong 2p-3d hybridizations, resulting in a depopulation of the 2p bands of O atoms, in comparison with other tested meta-GGAs. The regularized TPSS (regTPSS) and meta-GGAs made simple, i.e., MGGA_MS0 and MGGA_MS2, which are free of the spurious order-of-limits problem of TPSS and revTPSS, give electronic states close to those of the PBE GGA and LSDA. In comparison to experiment, semilocal functionals predict better equilibrium cell volumes for rutile VO2 in FM and AFM states than in the spin-unpolarized state. For meta-GGAs, a monotonic decrease of the exchange enhancement factor Fx(s,α) with α for small s, as in the MGGA_MS functionals, leads to large (probably too large) local magnetic moments in spin-polarized states.

  7. H-1 Nuclear Magnetic Resonance Metabolomics Analysis Identifies Novel Urinary Biomarkers for Lung Function

    SciTech Connect

    MCClay, Joseph L.; Adkins, Daniel E.; Isern, Nancy G.; O'Connell, Thomas M.; Wooten, Jan B.; Zedler, Barbara K.; Dasika, Madhukar S.; Webb, B. T.; Webb-Robertson, Bobbie-Jo M.; Pounds, Joel G.; Murrelle, Edward L.; Leppert, Mark F.; van den Oord, Edwin J.

    2010-06-04

    Chronic obstructive pulmonary disease (COPD), characterized by chronic airflow limitation, is a serious and growing public health concern. The major environmental risk factor for COPD is tobacco smoking, but the biological mechanisms underlying COPD are not well understood. In this study, we used proton nuclear magnetic resonance (1H-NMR) spectroscopy to identify and quantify metabolites associated with lung function in COPD. Plasma and urine were collected from 197 adults with COPD and from 195 adults without COPD. Samples were assayed using a 600 MHz NMR spectrometer, and the resulting spectra were analyzed against quantitative spirometric measures of lung function. After correcting for false discoveries and adjusting for covariates (sex, age, smoking) several spectral regions in urine were found to be significantly associated with baseline lung function. These regions correspond to the metabolites trigonelline, hippurate and formate. Concentrations of each metabolite, standardized to urinary creatinine, were associated with baseline lung function (minimum p-value = 0.0002 for trigonelline). No significant associations were found with plasma metabolites. Two of the three urinary metabolites positively associated with baseline lung function, i.e. hippurate and formate, are often related to gut microflora. This suggests that the microbiome composition is variable between individuals with different lung function. Alternatively, the nature and origins of all three associated metabolites may reflect lifestyle differences affecting overall health. Our results will require replication and validation, but demonstrate the utility of NMR metabolomics as a screening tool for identifying novel biomarkers of lung disease or disease risk.

  8. Using functional magnetic resonance imaging to explore the possible mechanism of the action of acupuncture at Dazhong (KI 4) on the functional cerebral regions of healthy volunteers.

    PubMed

    Zhang, Q; Li, A; Yue, J; Zhang, F; Sun, Z; Li, X

    2015-06-01

    Acupuncture at right Dazhong (KI 4) mostly affects functional magnetic resonance imaging signal in the right inferior frontal gyrus, right insular lobe, right thalamus, right middle frontal gyrus and right orbitofrontal cortex, which are associated with governing executive functions, emotional activities and social behaviour.

  9. Electrocatalytic features of a heme protein attached to polymer-functionalized magnetic nanoparticles.

    PubMed

    Krishnan, Sadagopan; Walgama, Charuksha

    2013-12-03

    Direct electron-transfer and electrocatalytic kinetics of covalently attached myoglobin (MB) films on magnetic nanoparticles (MB-MNP(covalent)), in comparison to the corresponding physisorbed films and individual components, are reported for the first time. MB-MNP(covalent) ("-" denotes a covalent linkage) was adsorbed onto a cationic poly(ethyleneimine) layer (PEI) coated high-purity graphite (HPG) electrode. Similarly, films of myoglobin physisorbed on magnetic nanoparticles (MB/MNP(adsorbed), "/" denotes a noncovalent nature), only MB, or only MNP were constructed on HPG/PEI electrodes for comparison. The observed electron-transfer rate constants (k(s), s(-1)) were in the following order: MB-MNP(covalent) (69 ± 6 s(-1)), MB/MNP(adsorbed) (37 ± 2 s(-1)), only MB (27 ± 2 s(-1)), and only MNP (16 ± 3 s(-1)). The electrocatalytic properties of these films were investigated with the aid of tert-butylhydroperoxide as a model reactant, and its reduction kinetics were examined. We observed the following order of catalytic current density: MB-MNP(covalent) > MB/MNP(adsorbed) > only MNP > only MB, in agreement with the electron-transfer (ET) rates of MB-MNP(covalent) and MB/MNP(adsorbed) films. The crucial function of MNP in favorably altering the direct ET and electrocatalytic properties of both covalently bound MB and physisorbed MB molecules are discussed. In addition, the occurrence of a highly enhanced electron-hopping mechanism in the designed covalent MB-MNP(covalent) films over the corresponding physisorbed MB/MNP(adsorbed) film is proposed. The enhanced electron-transfer rates and catalytic current density suggest the advantages of using metalloenzymes covalently attached to polymer-functionalized magnetic nanoparticles for the development of modern highly efficient miniature biosensors and bioreactors.

  10. Repetitive magnetic stimulation improves retinal function in a rat model of retinal dystrophy

    NASA Astrophysics Data System (ADS)

    Rotenstreich, Ygal; Tzameret, Adi; Levi, Nir; Kalish, Sapir; Sher, Ifat; Zangen, Avraham; Belkin, Michael

    2014-02-01

    Vision incapacitation and blindness associated with retinal dystrophies affect millions of people worldwide. Retinal degeneration is characterized by photoreceptor cell death and concomitant remodeling of remaining retinal cells. Repetitive Magnetic Stimulation (RMS) is a non-invasive technique that creates alternating magnetic fields by brief electric currents transmitted through an insulated coil. These magnetic field generate action potentials in neurons, and modulate the expression of neurotransmitter receptors, growth factors and transcription factors which mediate plasticity. This technology has been proven effective and safe in various psychiatric disorders. Here we determined the effect of RMS on retinal function in Royal College of Surgeons (RCS) rats, a model for retinal dystrophy. Four week-old RCS and control Spargue Dawley (SD) rats received sham or RMS treatment over the right eye (12 sessions on 4 weeks). RMS treatment at intensity of at 40% of the maximal output of a Rapid2 stimulator significantly increased the electroretinogram (ERG) b-wave responses by up to 6- or 10-fold in the left and right eye respectively, 3-5 weeks following end of treatment. RMS treatment at intensity of 25% of the maximal output did not significant effect b-wave responses following end of treatment with no adverse effect on ERG response or retinal structure of SD rats. Our findings suggest that RMS treatment induces delayed improvement of retinal functions and may induce plasticity in the retinal tissue. Furthermore, this non-invasive treatment may possibly be used in the future as a primary or adjuvant treatment for retinal dystrophy.

  11. Altered amygdala and hippocampus function in adolescents with hypercortisolemia: a functional magnetic resonance imaging study of Cushing syndrome.

    PubMed

    Maheu, Françoise S; Mazzone, Luigi; Merke, Deborah P; Keil, Margaret F; Stratakis, Constantine A; Pine, Daniel S; Ernst, Monique

    2008-01-01

    Chronic elevations of endogenous cortisol levels have been shown to alter medial temporal cortical structures and to be accompanied by declarative memory impairments and depressive symptoms in human adults. These effects of elevated endogenous levels of cortisol have not been directly studied in adolescents. Because adolescents with Cushing syndrome show endogenous elevations in cortisol, they represent a unique natural model to study the effects of prolonged hypercortisolemia on brain function, and memory and affective processes during this developmental stage. Using functional magnetic resonance imaging (fMRI), we compared 12 adolescents with Cushing syndrome with 22 healthy control adolescents on amygdala and anterior hippocampus activation during an emotional faces encoding task. None of these adolescents manifested depressive symptoms. Encoding success was assessed using a memory recognition test performed after the scan. The fMRI analyses followed an event-related design and were conducted using the SPM99 platform. Compared to healthy adolescents, patients with Cushing syndrome showed greater left amygdala and right anterior hippocampus activation during successful face encoding. Memory performance for faces recognition did not differ between groups. This first study of cerebral function in adolescents with chronic endogenous hypercortisolemia due to Cushing syndrome demonstrates the presence of functional alterations in amygdala and hippocampus, which are not associated with affective or memory impairments. Such findings need to be followed by work examining the role of age and related brain maturational stage on these effects, as well as the identification of possible protective factors conferring resilience to affective and cognitive consequences in this disease and/or during this stage of cerebral development.

  12. Nuclear magnetic resonance spectroscopy for determining the functional content of organic aerosols: a review.

    PubMed

    Chalbot, Marie-Cecile G; Kavouras, Ilias G

    2014-08-01

    The knowledge deficit of organic aerosol (OA) composition has been identified as the most important factor limiting our understanding of the atmospheric fate and implications of aerosol. The efforts to chemically characterize OA include the increasing utilization of nuclear magnetic resonance spectroscopy (NMR). Since 1998, the functional composition of different types, sizes and fractions of OA has been studied with one-dimensional, two-dimensional and solid state proton and carbon-13 NMR. This led to the use of functional group ratios to reconcile the most important sources of OA, including secondary organic aerosol and initial source apportionment using positive matrix factorization. Future research efforts may be directed towards the optimization of experimental parameters, detailed NMR experiments and analysis by pattern recognition methods to identify the chemical components, determination of the NMR fingerprints of OA sources and solid state NMR to study the content of OA as a whole.

  13. Statistical approaches to human brain mapping by functional magnetic resonance imaging.

    PubMed

    Lange, N

    1996-02-28

    Proper use of functional neuro-imaging through effective experimental design and modern statistical analysis provides new insights in current brain research. This tutorial has two aims: to describe aspects of this technology to applied statisticians and to provide some statistical ideas to neuroscientists unfamiliar with quantitative analytic methods that accommodate randomness. Introductory background material and ample references to current literature on the physics of magnetic resonance imaging, Fourier methods for image reconstruction and measures of image quality are included. Two of the statistical approaches mentioned here are extensions of established methods for longitudinal data analysis to the frequency domain. A recent case study provides real-world instances of approaches, problems and open questions encountered in current functional neuro-imaging research and an introduction to the analysis of spatial time series in this context.

  14. Source analysis of stimulus-preceding negativity constrained by functional magnetic resonance imaging.

    PubMed

    Kotani, Yasunori; Ohgami, Yoshimi; Ishiwata, Takayuki; Arai, Jun-Ichirou; Kiryu, Shigeru; Inoue, Yusuke

    2015-10-01

    The stimulus-preceding negativity (SPN) is an event-related potential (ERP) reflecting anticipation. The anterior insular cortex is assumed to be one of the physiological sources of the SPN. However, the precise neural substrates of the SPN have yet to be confirmed. We therefore performed separate functional magnetic resonance imaging (fMRI) and ERP studies using the same time estimation task, followed by fMRI-constrained ERP source analysis. Dipole locations were determined by the fMRI results, while the time courses of dipole activities were modeled by the ERP data. Analysis revealed that the right anterior insula was significantly activated before delivery of the feedback stimulus, whereas the left anterior insula was not, and that the SPN mainly arose from four groups of brain regions related to, respectively: (1) the salience network, (2) reward expectation, (3) perceptual anticipation, and (4) arousal. The results suggest that the SPN pertains to multiple brain functions with complex interactions.

  15. Magnetically induced behaviour of ferritin corpuscles in avian ears: can cuticulosomes function as magnetosomes?

    PubMed

    Jandacka, Petr; Burda, Hynek; Pistora, Jaromir

    2015-01-06

    Magnetoreception is an enigmatic, poorly understood sensory ability, described mainly on the basis of behavioural studies in animals of diverse taxa. Recently, corpuscles containing superparamagnetic iron-storage protein ferritin were found in the inner ear hair cells of birds, a predominantly single ferritin corpuscle per cell. It was suggested that these corpuscles might represent magnetosomes and function as magnetosensors. Here we determine ferritin low-field paramagnetic susceptibility to estimate its magnetically induced intracellular behaviour. Physical simulations show that ferritin corpuscles cannot be deformed or rotate in weak geomagnetic fields, and thus cannot provide magnetoreception via deformation of the cuticular plate. Furthermore, we reached an alternative hypothesis that ferritin corpuscle in avian ears may function as an intracellular electromagnetic oscillator. Such an oscillator would generate additional cellular electric potential related to normal cell conditions. Though the phenomenon seems to be weak, this effect deserves further analyses.

  16. Low-Functioning Autism and Nonsyndromic Intellectual Disability: Magnetic Resonance Imaging (MRI) Findings.

    PubMed

    Erbetta, Alessandra; Bulgheroni, Sara; Contarino, Valeria Elisa; Chiapparini, Luisa; Esposito, Silvia; Annunziata, Silvia; Riva, Daria

    2015-10-01

    Previous neuroradiologic studies reported a high incidence of abnormalities in low-functioning autistic children. In this population, it is difficult to know which abnormality depends on autism itself and which is related to intellectual disability associated with autism. The aim of this study was to evaluate the frequency of neuroradiologic abnormalities in low-functioning autistic children compared to Intellectual Quotient and age-matched nonsyndromic children, using the same set of magnetic resonance imaging (MRI) sequences. MRI was rated as abnormal in 44% of autistic and 54% of children with intellectual disability. The main results were mega cisterna magna in autism and hypoplastic corpus callosum in intellectual disability. These abnormalities are morphologically visible signs of altered brain development. These findings, more frequent than expected, are not specific to the 2 conditions. Although MRI cannot be considered mandatory, it allows an in-depth clinical assessment in nonsyndromic intellectual-disabled and autistic children.

  17. Hierarchically functionalized magnetic core/multishell particles and their postsynthetic conversion to polymer capsules.

    PubMed

    Schmitt, Sophia; Silvestre, Martin; Tsotsalas, Manuel; Winkler, Anna-Lena; Shahnas, Artak; Grosjean, Sylvain; Laye, Fabrice; Gliemann, Hartmut; Lahann, Joerg; Bräse, Stefan; Franzreb, Matthias; Wöll, Christof

    2015-01-01

    The controlled synthesis of hierarchically functionalized core/multishell particles is highly desirable for applications in medicine, catalysis, and separation. Here, we describe the synthesis of hierarchically structured metal-organic framework multishells around magnetic core particles (magMOFs) via layer-by-layer (LbL) synthesis. The LbL deposition enables the design of multishell systems, where each MOF shell can be modified to install different functions. Here, we used this approach to create controlled release capsules, in which the inner shell serves as a reservoir and the outer shell serves as a membrane after postsynthetic conversion of the MOF structure to a polymer network. These capsules enable the controlled release of loaded dye molecules, depending on the surrounding media.

  18. Magnetic Resonance Spectroscopy As a Tool for Assessing Macromolecular Structure and Function in Living Cells.

    PubMed

    Li, Conggangg; Zhao, Jiajing; Cheng, Kai; Ge, Yuwei; Wu, Qiong; Ye, Yansheng; Xu, Guohua; Zhang, Zeting; Zheng, Wenwen; Zhang, Xu; Zhou, Xin; Pielak, Gary; Liu, Maili

    2017-03-09

    Investigating the structure, modification, interaction, and function of biomolecules in their native cellular environment leads to physiologically relevant knowledge about their mechanisms, which will benefit drug discovery and design. In recent years, nuclear and electron magnetic resonance (NMR) spectroscopy has emerged as a useful tool for elucidating the structure and function of biomacromolecules, including proteins, nucleic acids, and carbohydrates in living cells at atomic resolution. In this review, we summarize the progress and future of in-cell NMR as it is applied to proteins, nucleic acids, and carbohydrates. Expected final online publication date for the Annual Review of Analytical Chemistry Volume 10 is June 12, 2017. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  19. Functionalized magnetic nanoparticles for the decontamination of water polluted with cesium

    NASA Astrophysics Data System (ADS)

    Helal, Ahmed S.; Decorse, Philippe; Perruchot, Christian; Novak, Sophie; Lion, Claude; Ammar, Souad; El Hage Chahine, Jean-Michel; Hémadi, Miryana

    2016-05-01

    Magnetic nanoparticles are attracting considerable interest because of their potential applications in practically all fields of science and technology, including the removal of heavy metals from contaminated waters. It is, therefore, of great importance to adapt the surfaces of these nanoparticles according to the application. In this work advanced nanoparticles (NPs) with well-tailored surface functionalities were synthesized using the polyol method. The efficiency of a chelating agent, succinyl-β-cyclodextrin (SBCD), was first investigated spectrophotometrically and by Isothermal Titration Calorimetry (ITC). SBCD was then grafted onto nanoparticles previously functionalized with 3-aminopropyl triethoxsilane (NP-APTES). The resulting NP-SBCD system was then incubated with a solution of cesium. After magnetic separation, the solid residue was removed from the supernatant and characterized by X-Ray Photoelectron spectrometry (XPS), X-Ray Fluorescence spectrometry (XRF) and Superconducting QUantum Interference Device (SQUID) magnetometry. These characterizations show the presence of cesium in the solid residue, which indicates Cs uptake by the NP-SBCD system. This nanohybrid system constitutes a promising model for heavy metal decontamination.

  20. Magnetic hydrogels from alkyne/cobalt carbonyl-functionalized ABA triblock copolymers

    DOE PAGES

    Jiang, Bingyin; Hom, Wendy L.; Chen, Xianyin; ...

    2016-03-09

    A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)-block-poly(ethylene oxide)-block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. PESn[Co2(CO)6]x-EO800-PESn[Co2(CO)6]x ABA triblock copolymer/cobalt adducts (10–67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co2(CO)8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linked materials with water. Furthermore, swelling tests, rheological studies and actuation tests demonstrated thatmore » the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors.« less

  1. Magnetic hydrogels from alkyne/cobalt carbonyl-functionalized ABA triblock copolymers

    SciTech Connect

    Jiang, Bingyin; Hom, Wendy L.; Chen, Xianyin; Yu, Pengqing; Pavelka, Laura C.; Kisslinger, Kim; Parise, John B.; Bhatia, Surita R.; Grubbs, Robert B.

    2016-03-09

    A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)-block-poly(ethylene oxide)-block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. PESn[Co2(CO)6]x-EO800-PESn[Co2(CO)6]x ABA triblock copolymer/cobalt adducts (10–67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co2(CO)8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linked materials with water. Furthermore, swelling tests, rheological studies and actuation tests demonstrated that the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors.

  2. Effect of midazolam on memory: a study of process dissociation procedure and functional magnetic resonance imaging.

    PubMed

    Tian, S Y; Zou, L; Quan, X; Zhang, Y; Xue, F S; Ye, T H

    2010-06-01

    To assess the effects of midazolam on explicit and implicit memories, 12 volunteers were randomly divided into the two groups: one with an Observer's Assessment of Alertness/Sedation score of 3 (mild sedation) and one with a score of 1 (deep sedation). Blood oxygen-level-dependent functional magnetic resonance imaging was measured before and during an auditory stimulus, then with midazolam sedation, and then during a second auditory stimulus with continuous midazolam sedation. After 4 h, explicit and implicit memories were assessed. There was no evidence of explicit memory at the two levels of midazolam sedation. Implicit memory was retained at a mild level of midazolam sedation but absent at a deep level of midazolam sedation. At a mild level of midazolam sedation, activation of all brain areas by auditory stimulus (as measured by functional magnetic resonance imaging) was uninhibited. However, a deep level of midazolam sedation depressed activation of the superior temporal gyrus by auditory stimulus. We conclude that midazolam does not abolish implicit memory at a mild sedation level, but can abolish both explicit and implicit memories at a deep sedation level. The superior temporal gyrus may be one of the target areas.

  3. Magnetic nanoparticles coated with maltose-functionalized polyethyleneimine for highly efficient enrichment of N-glycopeptides.

    PubMed

    Li, Jinan; Wang, Fangjun; Wan, Hao; Liu, Jing; Liu, Zheyi; Cheng, Kai; Zou, Hanfa

    2015-12-18

    Hydrophilic interaction chromatography (HILIC) adsorbents have drawn increasing attention in recent years due to their high efficiency in N-glycopeptides enrichment. The hydrophilicity and binding capacity of HILIC adsorbents are crucial to the enrichment efficiency and mass spectrometry (MS) detection sensitivity of N-glycopeptides. Herein, magnetic nanoparticles coated with maltose-functionalized polyethyleneimine (Fe3O4-PEI-Maltose MNPs) were prepared by one-pot solvothermal reaction coupled with "click chemistry" and utilized for N-glycopeptides enrichment. Owing to the presence of hydrophilic and branched polyethyleneimine, the amount of immobilized disaccharide units was improved about four times. The N-glycopeptides capturing capacity was about 150mg/g (IgG/MNPs) and the MS detection limitation as low as 0.5fmol for IgG and 85% average enrichment recovery were feasibly achieved by using this hybrid magnetic adsorbent. Finally, 1237 unique N-glycosylation sites and 1567 unique N-glycopeptides from 684 N-glycoproteins were reliably characterized from 60μg protein sample extracted from mouse liver. Therefore, this maltose-functionalized polyethyleneimine coated adsorbent can play a promising role in highly efficient N-glycopeptides enrichment for glycoproteomic analyses of complex protein samples.

  4. Frequency Clustering Analysis for Resting State Functional Magnetic Resonance Imaging Based on Hilbert-Huang Transform

    PubMed Central

    Wu, Xia; Wu, Tong; Liu, Chenghua; Wen, Xiaotong; Yao, Li

    2017-01-01

    Objective: Exploring resting-state functional networks using functional magnetic resonance imaging (fMRI) is a hot topic in the field of brain functions. Previous studies suggested that the frequency dependence between blood oxygen level dependent (BOLD) signals may convey meaningful information regarding interactions between brain regions. Methods: In this article, we introduced a novel frequency clustering analysis method based on Hilbert-Huang Transform (HHT) and a label-replacement procedure. First, the time series from multiple predefined regions of interest (ROIs) were extracted. Second, each time series was decomposed into several intrinsic mode functions (IMFs) by using HHT. Third, the improved k-means clustering method using a label-replacement method was applied to the data of each subject to classify the ROIs into different classes. Results: Two independent resting-state fMRI dataset of healthy subjects were analyzed to test the efficacy of method. The results show almost identical clusters when applied to different runs of a dataset or to different datasets, indicating a stable performance of our framework. Conclusions and Significance: Our framework provided a novel measure for functional segregation of the brain according to time-frequency characteristics of resting state BOLD activities. PMID:28261074

  5. Neurofeedback of two motor functions using supervised learning-based real-time functional magnetic resonance imaging.

    PubMed

    Papageorgiou, T Dorina; Curtis, William A; McHenry, Monica; LaConte, Stephen M

    2009-01-01

    This study examines the effects of neurofeedback provided by support vector machine (SVM) classification-based real-time functional magnetic resonance imaging (rt-fMRI) during two types of motor tasks. This approach also enables the examination of the neural regions associated with predicting mental states in different domains of motor control, which is critical to further our understanding of normal and impaired function. Healthy volunteers (n = 13) performed both a simple button tapping task, and a covert rate-of-speech counting task. The average prediction accuracy was approximately 95% for the button tapping task and 86% for the speech task. However, subsequent offline analysis revealed that classification of the initial runs was significantly lower - 75% (p<0.001) for button and 72% (p<0.005) for speech. To explore this effect, a group analysis was performed using the spatial maps derived from the SVM models, which showed significant differences between the two fMRI runs. One possible explanation for the difference in spatial patterns and the asymmetry in the prediction accuracies is that when subjects are actively engaged in the task (i.e. when they are trying to control a computer interface), they are generating stronger BOLD responses in terms of both intensity and spatial extent.

  6. Acquired aplastic anemia.

    PubMed

    Keohane, Elaine M

    2004-01-01

    Acquired aplastic anemia (AA) is a disorder characterized by a profound deficit of hematopoietic stem and progenitor cells, bone marrow hypocellularity, and peripheral blood pancytopenia. It primarily affects children, young adults, and those over 60 years of age. The majority of cases are idiopathic; however, idiosyncratic reactions to some drugs, chemicals, and viruses have been implicated in its etiology. An autoimmune T-cell reaction likely causes the stem cell depletion, but the precise mechanism, as well as the eliciting and target antigens, is unknown. Symptoms vary from severe life-threatening cytopenias to moderate or non-severe disease that does not require transfusion support. The peripheral blood typically exhibits pancytopenia, reticulocytopenia, and normocytic or macrocytic erythrocytes. The bone marrow is hypocellular and may exhibit dysplasia of the erythrocyte precursors. First line treatment for severe AA consists of hematopoietic stem cell transplantation in young patients with HLA identical siblings, while immunosuppression therapy is used for older patients and for those of any age who lack a HLA matched donor. Patients with AA have an increased risk of developing paroxysmal nocturnal hemoglobinuria (PNH), myelodysplastic syndrome (MDS), or acute leukemia. Further elucidation of the pathophysiology of this disease will result in a better understanding of the interrelationship among AA, PNH, and MDS, and may lead to novel targeted therapies.

  7. Acquired spatial dyslexia.

    PubMed

    Siéroff, E

    2015-08-10

    Acquired spatial dyslexia is a reading disorder frequently occurring after left or right posterior brain lesions. This article describes several types of spatial dyslexia with an attentional approach. After right posterior lesions, patients show left neglect dyslexia with errors on the left side of text, words, and non-words. The deficit is frequently associated with left unilateral spatial neglect. Severe left neglect dyslexia can be detected with unlimited exposure duration of words or non-words. Minor neglect dyslexia is detected with brief presentation of bilateral words, one in the left and one in the right visual field (phenomenon of contralesional extinction). Neglect dyslexia can be explained as a difficulty in orienting attention to the left side of verbal stimuli. With left posterior lesions, spatial dyslexia is also frequent but multiform. Right neglect dyslexia is frequent, but right unilateral spatial neglect is rare. Attentional dyslexia represents difficulty in selecting a stimulus, letter or word among other similar stimuli; it is a deficit of attentional selection, and the left hemisphere plays a crucial role in selection. Two other types of spatial dyslexia can be found after left posterior lesions: paradoxical ipsilesional extinction and stimulus-centred neglect dyslexia. Disconnections between left or right parietal attentional areas and the left temporal visual word form area could explain these deficits. Overall, a model of attention dissociating modulation, selection control, and selection positioning can help in understanding these reading disorders.

  8. Seeing mathematics: perceptual experience and brain activity in acquired synesthesia.

    PubMed

    Brogaard, Berit; Vanni, Simo; Silvanto, Juha

    2013-01-01

    We studied the patient JP who has exceptional abilities to draw complex geometrical images by hand and a form of acquired synesthesia for mathematical formulas and objects, which he perceives as geometrical figures. JP sees all smooth curvatures as discrete lines, similarly regardless of scale. We carried out two preliminary investigations to establish the perceptual nature of synesthetic experience and to investigate the neural basis of this phenomenon. In a functional magnetic resonance imaging (fMRI) study, image-inducing formulas produced larger fMRI responses than non-image inducing formulas in the left temporal, parietal and frontal lobes. Thus our main finding is that the activation associated with his experience of complex geometrical images emerging from mathematical formulas is restricted to the left hemisphere.

  9. Immature myeloid Gr-1+ CD11b+ cells from lipopolysaccharide-immunosuppressed mice acquire inhibitory activity in the bone marrow and migrate to lymph nodes to exert their suppressive function.

    PubMed

    Landoni, Veronica I; Martire-Greco, Daiana; Rodriguez-Rodrigues, Nahuel; Chiarella, Paula; Schierloh, Pablo; Isturiz, Martin A; Fernández, Gabriela C

    2016-02-01

    Secondary infections due to post-sepsis immunosuppression are a major cause of death in patients with sepsis. Repetitive inoculation of increasing doses of lipopolysaccharide (LPS) into mice mimics the immunosuppression associated with sepsis. Myeloid-derived suppressor cells (MDSCs, Gr-1(+) CD11b(+)) are considered a major component of the immunosuppressive network, interfering with T-cell responses in many pathological conditions. We used LPS-immunosuppressed (IS) mice to address whether MDSCs acquired their suppressive ability in the bone marrow (BM) and whether they could migrate to lymph nodes (LNs) to exert their suppressive function. Our results showed that Gr-1(+) CD11b(+) cells of IS mice already had the potential to inhibit T-cell proliferation in the BM. Moreover, soluble factors present in the BM from IS mice were responsible for inducing this inhibitory ability in control BM cells. In addition, migration of Gr-1(+) CD11b(+) to LNs in vivo was maximal when cells obtained from the BM of IS mice were inoculated into an IS context. In this regard, we found chemoattractant activity in cell-free LN extracts (LNEs) from IS mice and an increased expression of the LN-homing chemokine receptor C-C chemokine receptor type 7 (CCR7) in IS BM Gr-1(+) CD11b(+) cells. These results indicate that Gr-1(+) CD11b(+) cells found in BM from IS mice acquire their suppressive activity in the same niche where they are generated, and migrate to LNs to exert their inhibitory role. A better understanding of MDSC generation and/or regulation of factors able to induce their inhibitory function may provide new and more effective tools for the treatment of sepsis-associated immunosuppression.

  10. Magnetism, structures and stabilities of cluster assembled TM@Si nanotubes (TM = Cr, Mn and Fe): a density functional study.

    PubMed

    Dhaka, Kapil; Bandyopadhyay, Debashis

    2016-08-02

    The present study reports transition metal (TM = Cr, Mn and Fe) doped silicon nanotubes with tunable band structures and magnetic properties by careful selection of cluster assemblies as building blocks using the first-principles density functional theory. We found that the transition metal doping and in addition, the hydrogen termination process can stabilize the pure silicon nanoclusters or cluster assemblies and then it could be extended as magnetic nanotubes with finite magnetic moments. Study of the band structures and density of states (DOS) of different empty and TM doped nanotubes (Type 1 to Type 4) show that these nanotubes are useful as metals, semiconductors, semi-metals and half-metals. These designer magnetic materials could be useful in spintronics and magnetic devices of nanoscale order.

  11. Evolution of an electron energy distribution function in a weak dc magnetic field in solenoidal inductive plasma

    SciTech Connect

    Lee, Min-Hyong; Choi, Seong Wook

    2008-12-01

    We investigated the evolution of the electron energy distribution function (EEDF) in a solenoidal inductively coupled plasma surrounded by an axial dc magnetic field. The increase in the dc magnetic field caused the EEDF to evolve from a bi-Maxwellian to a Maxwellian distribution. At the discharge center, the number of low energy electrons was significantly reduced while the high energy electron population showed little change when a weak dc magnetic field was present. However, at the discharge radial boundary, the high energy electron population decreased significantly with the magnetic field while the change in low energy population was not prominent compared to the discharge boundary. These changes in EEDFs at the boundary and center of the discharge are due to the radial confinement and the restriction of radial transport of electrons by dc magnetic field.

  12. Vacancy-induced magnetism in BaTiO3(001) thin films based on density functional theory.

    PubMed

    Cao, Dan; Cai, Meng-Qiu; Hu, Wang-Yu; Yu, Ping; Huang, Hai-Tao

    2011-03-14

    The origin of magnetism induced by vacancies on BaTiO(3)(001) surfaces is investigated systematically by first-principles calculations within density-functional theory. The calculated results show that O vacancy is responsible for the magnetism of the BaO-terminated surface and the magnetism of the TiO(2)-terminated surface is induced by Ti vacancy. For the BaO-terminated surface, the magnetism mainly arises from the unpaired electrons that are localized in the O vacancy basin. In contrast, for the TiO(2)-terminated surface, the magnetism mainly originates from the partially occupied O-2p states of the first nearest neighbor O atoms surrounding the Ti vacancy. These results suggest the possibility of implementing magneto-electric coupling in conventional ferroelectric materials.

  13. A density functional study of strong local magnetism creation on MoS2 nanoribbon by sulfur vacancy.

    PubMed

    Shidpour, Reza; Manteghian, Merhrdad

    2010-08-01

    In this study a low-width MoS(2) ribbon has been used for probing the electronic structure and local magnetic moment near vacancies. A theoretical study with the full-potential Density Functional Theory (DFT) approach (Wien2K code) have shown that when the dimension of MoS(2) is reduced from 2-D to 1-D the nonmagnetic semi-conductor MoS(2) becomes a magnetic conductor. Our study has shown that a vacancy on the S-edge with 50% coverage intensifies the magnetization of the edge of the MoS(2) nanoribbon but such a vacancy on S-edge with 100% coverage causes this magnetic property to disappear. It is concluded that in both of them, there are positive or negative strong gradients of local magnetic moment near the vacancy. This may explain why lattice defects are essential for catalysis processes.

  14. A density functional study of strong local magnetism creation on MoS2 nanoribbon by sulfur vacancy

    NASA Astrophysics Data System (ADS)

    Shidpour, Reza; Manteghian, Merhrdad

    2010-08-01

    In this study a low-width MoS2 ribbon has been used for probing the electronic structure and local magnetic moment near vacancies. A theoretical study with the full-potential Density Functional Theory (DFT) approach (Wien2K code) have shown that when the dimension of MoS2 is reduced from 2-D to 1-D the nonmagnetic semi-conductor MoS2 becomes a magnetic conductor. Our study has shown that a vacancy on the S-edge with 50% coverage intensifies the magnetization of the edge of the MoS2 nanoribbon but such a vacancy on S-edge with 100% coverage causes this magnetic property to disappear. It is concluded that in both of them, there are positive or negative strong gradients of local magnetic moment near the vacancy. This may explain why lattice defects are essential for catalysis processes.

  15. Affinity capture using peptide-functionalized magnetic nanoparticles to target Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Kuo, Fang-Yin; Lin, Wei-Lien; Chen, Yu-Chie

    2016-04-01

    Staphylococcus aureus, a commonly found pathogen, can cause food poisoning and infections. Thus, it is necessary to develop analytical methods for the rapid screening of S. aureus in suspicious samples. Magnetic nanoparticles (MNPs) are widely used as affinity probes to selectively enrich target species from complex samples because of their high specific surface area and magnetic properties. The MNP surface should be functionalized to have the capability to target specific species. We herein propose a straightforward method to functionalize aluminum oxide-coated iron oxide (Fe3O4@Al2O3) MNPs with the peptide HHHHHHDEEGLFVD (D). The peptide D was comprised of three domains: polyhistidine (H6) used as the linker, DEE added as the spacer, and GLFVD used for targeting S. aureus. D was immobilized on the surface of Fe3O4@Al2O3 MNPs through H6-Al chelation. Our results showed that the D-functionalized Fe3O4@Al2O3 MNPs (D-Fe3O4 MNPs) possess the capability to target S. aureus. The selective trapping experiments were conducted under microwave-heating for only 60 s, and sufficient bacterial cells were trapped by the MNPs to be identified by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). We demonstrated that the D-Fe3O4@Al2O3 MNPs combined with MALDI-MS can be used to rapidly characterize trace amounts of S. aureus in complex juice and egg samples.Staphylococcus aureus, a commonly found pathogen, can cause food poisoning and infections. Thus, it is necessary to develop analytical methods for the rapid screening of S. aureus in suspicious samples. Magnetic nanoparticles (MNPs) are widely used as affinity probes to selectively enrich target species from complex samples because of their high specific surface area and magnetic properties. The MNP surface should be functionalized to have the capability to target specific species. We herein propose a straightforward method to functionalize aluminum oxide-coated iron oxide (Fe3O4@Al2O3) MNPs with the

  16. Acquired reactive perforating collagenosis

    PubMed Central

    Fei, Chengwen; Wang, Yao; Gong, Yu; Xu, Hui; Yu, Qian; Shi, Yuling

    2016-01-01

    Abstract Background: Reactive perforating collagenosis (RPC) is a rare form of transepithelial elimination, in which altered collagen is extruded through the epidermis. There are 2 types of RPC, acquired RPC (ARPC) and inherited RPC, while the latter is extremely rare. Here we report on 1 case of ARPC. Methods: A 73-year-old female was presented with strongly itchy papules over her back and lower limbs for 3 months. She denied the history of oozing or vesiculation. A cutaneous examination showed diffusely distributed multiple well-defined keratotic papules, 4 to 10 mm in diameter, on the bilateral lower limbs and back as well as a few papules on her chest and forearm. Scratching scars were over the resolved lesions while Koebner phenomenon was negative. The patient had a history of type 2 diabetes for 15 years. Laboratory examinations showed elevated blood glucose level. Skin lesion biopsy showed a well-circumscribed area of necrosis filled with a keratotic plug. Parakeratotic cells and lymphocytic infiltration could be seen in the necrosed area. In dermis, sparse fiber bundles were seen perforating the epidermis. These degenerated fiber bundles were notarized as collagen fiber by elastic fiber stain, suggesting a diagnosis of RPC. Results: Then a diagnosis of ARPC was made according to the onset age and the history of diabetes mellitus. She was treated with topical application of corticosteroids twice a day and oral antihistamine once a day along with compound glycyrrhizin tablets 3 times a day. And the blood glucose was controlled in a satisfying range. Two months later, a significant improvement was seen in this patient. Conclusion: Since there is no efficient therapy to RPC, moreover, ARPC is considered to be associated with some systemic diseases, the management of the coexisting disease is quite crucial. The patient in this case received a substantial improvement due to the control of blood glucose and application of compound glycyrrhizin tablets. PMID

  17. Modulation of monocytic leukemia cell function and survival by high gradient magnetic fields and mathematical modeling studies.

    PubMed

    Zablotskii, Vitalii; Syrovets, Tatiana; Schmidt, Zoe W; Dejneka, Alexandr; Simmet, Thomas

    2014-03-01

    The influence of spatially modulated high gradient magnetic fields on cellular functions of human THP-1 leukemia cells is studied. We demonstrate that arrays of high-gradient micrometer-sized magnets induce i) cell swelling, ii) prolonged increased ROS production, and iii) inhibit cell proliferation, and iv) elicit apoptosis of THP-1 monocytic leukemia cells in the absence of chemical or biological agents. Mathematical modeling indicates that mechanical stress exerted on the cells by high magnetic gradient forces is responsible for triggering cell swelling and formation of reactive oxygen species followed by apoptosis. We discuss physical aspects of controlling cell functions by focused magnetic gradient forces, i.e. by a noninvasive and nondestructive physical approach.

  18. Cardiac Structure and Function in Cushing's Syndrome: A Cardiac Magnetic Resonance Imaging Study

    PubMed Central

    Roux, Charles; Salenave, Sylvie; Kachenoura, Nadjia; Raissouni, Zainab; Macron, Laurent; Guignat, Laurence; Jublanc, Christel; Azarine, Arshid; Brailly, Sylvie; Young, Jacques; Mousseaux, Elie; Chanson, Philippe

    2014-01-01

    Background: Patients with Cushing's syndrome have left ventricular (LV) hypertrophy and dysfunction on echocardiography, but echo-based measurements may have limited accuracy in obese patients. No data are available on right ventricular (RV) and left atrial (LA) size and function in these patients. Objectives: The objective of the study was to evaluate LV, RV, and LA structure and function in patients with Cushing's syndrome by means of cardiac magnetic resonance, currently the reference modality in assessment of cardiac geometry and function. Methods: Eighteen patients with active Cushing's syndrome and 18 volunteers matched for age, sex, and body mass index were studied by cardiac magnetic resonance. The imaging was repeated in the patients 6 months (range 2–12 mo) after the treatment of hypercortisolism. Results: Compared with controls, patients with Cushing's syndrome had lower LV, RV, and LA ejection fractions (P < .001 for all) and increased end-diastolic LV segmental thickness (P < .001). Treatment of hypercortisolism was associated with an improvement in ventricular and atrial systolic performance, as reflected by a 15% increase in the LV ejection fraction (P = .029), a 45% increase in the LA ejection fraction (P < .001), and an 11% increase in the RV ejection fraction (P = NS). After treatment, the LV mass index and end-diastolic LV mass to volume ratio decreased by 17% (P < .001) and 10% (P = .002), respectively. None of the patients had late gadolinium myocardial enhancement. Conclusion: Cushing's syndrome is associated with subclinical biventricular and LA systolic dysfunctions that are reversible after treatment. Despite skeletal muscle atrophy, Cushing's syndrome patients have an increased LV mass, reversible upon correction of hypercortisolism. PMID:25093618

  19. Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets

    SciTech Connect

    Antipov, Sergey

    2017-01-01

    Electron cloud instabilities affect the performance of many circular high-intensity particle accelerators. They usually have a fast growth rate and might lead to an increase of the transverse emittance and beam loss. A peculiar example of such an instability is observed in the Fermilab Recycler proton storage ring. Although this instability might pose a challenge for future intensity upgrades, its nature had not been completely understood. The phenomena has been studied experimentally by comparing the dynamics of stable and unstable beam, numerically by simulating the build-up of the electron cloud and its interaction with the beam, and analytically by constructing a model of an electron cloud driven instability with the electrons trapped in combined function dipoles. Stabilization of the beam by a clearing bunch reveals that the instability is caused by the electron cloud, trapped in beam optics magnets. Measurements of microwave propagation confirm the presence of the cloud in the combined function dipoles. Numerical simulations show that up to 10$^{-2}$ of the particles can be trapped by their magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a combined function dipole this multi-turn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The estimated fast instability growth rate of about 30 revolutions and low mode frequency of 0.4 MHz are consistent with experimental observations and agree with the simulations. The created instability model allows investigating the beam stability for the future intensity upgrades.

  20. Multimodal morphometry and functional magnetic resonance imaging in schizophrenia and auditory hallucinations

    PubMed Central

    García-Martí, Gracián; Aguilar, Eduardo Jesús; Martí-Bonmatí, Luis; Escartí, M José; Sanjuán, Julio

    2012-01-01

    AIM: To validate a multimodal [structural and functional magnetic resonance (MR)] approach as coincidence brain clusters are hypothesized to correlate with clinical severity of auditory hallucinations. METHODS: Twenty-two patients meeting Diagnostic and Statistical Manual of Mental Disorders (fourth edition, DSM-IV) criteria for schizophrenia and experiencing persistent hallucinations together with 28 healthy controls were evaluated with structural and functional MR imaging with an auditory paradigm designed to replicate those emotions related to the patients’ hallucinatory experiences. Coincidence maps were obtained by combining structural maps of gray matter reduction with emotional functional increased activation. Abnormal areas were correlated with the brief psychiatric rating scale (BPRS) and the psychotic symptom rating scale (PSYRATS) scales. RESULTS: The coincidence analysis showed areas with coexistence gray matter reductions and emotional activation in bilateral middle temporal and superior temporal gyri. Significant negative correlations between BPRS and PSYRATS scales were observed. BPRS scores were negatively correlated in the middle temporal gyrus (right) (t = 6.86, P = 0.001), while negative PSYRATS correlation affected regions in both the superior temporal gyrus (left) (t = 7.85, P = 0.001) and middle temporal gyrus (left) (t = 4.97, P = 0.002). CONCLUSION: Our data identify left superior and middle temporal gyri as relevant areas for the understanding of auditory hallucinations in schizophrenia. The use of multimodal approaches, sharing structural and functional information, may demonstrate areas specifically linked to the severity of auditory hallucinations. PMID:22590670

  1. Effects of Repetitive Transcranial Magnetic Stimulation Over Trunk Motor Spot on Balance Function in Stroke Patients

    PubMed Central

    2016-01-01

    Objective To assess the efficacy of high-frequency repetitive transcranial magnetic stimulation (rTMS) on balance function in patients with chronic stroke. Methods Thirty participants with chronic stroke were enrolled in this study. High frequency (10 Hz) rTMS was delivered with butterfly-coil on trunk motor spot. Each patient received both real and sham rTMS in a random sequence. The rTMS cycles (real or sham) were composed of 10 sessions each, administered over two weeks, and separated by a 4-week washout period. Balance function was measured by Berg Balance Scale and computerized dynamic posturography to determine the effect of rTMS before and one day after the end of each treatment period, as well as at a 1-month follow-up. Results The balance function was significantly improved after high frequency rTMS as compared with that after sham rTMS (p<0.05). There was no serious adverse effect in patients during the treatment period. Conclusion In the chronic stroke patients, high frequency rTMS to the trunk motor area seems to be a helpful way to improve balance function without any specific adverse effects. Further studies are needed to identify the underlying mechanism and generate a detailed protocol. PMID:27847712

  2. Effects of repetitive transcranial magnetic stimulation on recovery of function after spinal cord injury.

    PubMed

    Tazoe, Toshiki; Perez, Monica A

    2015-04-01

    A major goal of rehabilitation strategies after spinal cord injury (SCI) is to enhance the recovery of function. One possible avenue to achieve this goal is to strengthen the efficacy of the residual neuronal pathways. Noninvasive repetitive transcranial magnetic stimulation (rTMS) has been used in patients with motor disorders as a tool to modulate activity of corticospinal, cortical, and subcortical pathways to promote functional recovery. This article reviews a series of studies published during the last decade that used rTMS in the acute and chronic stages of paraplegia and tetraplegia in humans with complete and incomplete SCI. In the studies, rTMS has been applied over the arm and leg representations of the primary motor cortex to target 3 main consequences of SCI: sensory and motor function impairments, spasticity, and neuropathic pain. Although some studies demonstrated that consecutive sessions of rTMS improve aspects of particular functions, other studies did not show similar effects. We discuss how rTMS parameters and postinjury reorganization in the corticospinal tract, motor cortical, and spinal cord circuits might be critical factors in understanding the advantages and disadvantages of using rTMS in patients with SCI. The available data highlight the limited information on the use of rTMS after SCI and the need to further understand the pathophysiology of neuronal structures affected by rTMS to maximize the potential beneficial effects of this technique in humans with SCI.

  3. Functional magnetic resonance imaging exploration of combined hand and speech movements in Parkinson's disease.

    PubMed

    Pinto, Serge; Mancini, Laura; Jahanshahi, Marjan; Thornton, John S; Tripoliti, Elina; Yousry, Tarek A; Limousin, Patricia

    2011-10-01

    Among the repertoire of motor functions, although hand movement and speech production tasks have been investigated widely by functional neuroimaging, paradigms combining both movements have been studied less so. Such paradigms are of particular interest in Parkinson's disease, in which patients have specific difficulties performing two movements simultaneously. In 9 unmedicated patients with Parkinson's disease and 15 healthy control subjects, externally cued tasks (i.e., hand movement, speech production, and combined hand movement and speech production) were performed twice in a random order and functional magnetic resonance imaging detected cerebral activations, compared to the rest. F-statistics tested within-group (significant activations at P values < 0.05, familywise error corrected), between-group, and between-task comparisons (regional activations significant at P values < 0.001, uncorrected, with cluster size > 10 voxels). For control subjects, the combined task activations comprised the sum of those obtained during hand movement and speech production performed separately, reflecting the neural correlates of performing movements sharing similar programming modalities. In patients with Parkinson's disease, only activations underlying hand movement were observed during the combined task. We interpreted this phenomenon as patients' potential inability to recruit facilitatory activations while performing two movements simultaneously. This lost capacity could be related to a functional prioritization of one movement (i.e., hand movement), in comparison with the other (i.e., speech production). Our observation could also reflect the inability of patients with Parkinson's disease to intrinsically engage the motor coordination necessary to perform a combined task.

  4. Group Treatment in Acquired Brain Injury Rehabilitation

    ERIC Educational Resources Information Center

    Bertisch, Hilary; Rath, Joseph F.; Langenbahn, Donna M.; Sherr, Rose Lynn; Diller, Leonard

    2011-01-01

    The current article describes critical issues in adapting traditional group-treatment methods for working with individuals with reduced cognitive capacity secondary to acquired brain injury. Using the classification system based on functional ability developed at the NYU Rusk Institute of Rehabilitation Medicine (RIRM), we delineate the cognitive…

  5. Electronic and magnetic properties of N-N split substitution in GaAs: A hybrid density functional study

    SciTech Connect

    Huang, Ruiqi; Wang, Qingxia; Cai, Xiaolin; Li, Chong; Jia, Yu; Wang, Fei; Wang, Sanjun

    2015-07-15

    Employing the first-principles combined with hybrid functional calculations, the electronic and magnetic properties of GaAs doped with a N{sub 2} molecule are investigated in this work. We find that in Ga{sub 32}As{sub 31}(N{sub 2}){sub As} the N-N split is able to saturate the dangling bond of Ga atom ,form sp{sup 3}-like hybridization, and simultaneously supply an extra localized electron, leading to a magnetic ground state with a magnetic moment of ∼1μ{sub B}. This magnetic ground state is different from previously nonmagnetic results predicted by PBE functional, which results from the self-interaction error inherent in semi-local density functional theory. Moreover, the band gap of magnetic ground state of Ga{sub 32}As{sub 31}(N{sub 2}){sub As} alloy decreases, which is relative to GaAs . Finally we discuss and explain why the magnetism is not discovered in previous experiments and theories.

  6. SACICA: a sparse approximation coefficient-based ICA model for functional magnetic resonance imaging data analysis.

    PubMed

    Wang, Nizhuan; Zeng, Weiming; Chen, Lei

    2013-05-30

    Independent component analysis (ICA) has been widely used in functional magnetic resonance imaging (fMRI) data to evaluate the functional connectivity, which assumes that the sources of functional networks are statistically independent. Recently, many researchers have demonstrated that sparsity is an effective assumption for fMRI signal separation. In this research, we present a sparse approximation coefficient-based ICA (SACICA) model to analyse fMRI data, which is a promising combination model of sparse features and an ICA technique. The SACICA method consists of three procedures. The wavelet packet decomposition procedure, which decomposes the fMRI data into wavelet tree nodes with different degrees of sparsity, is first. Then, the sparse approximation coefficients set formation procedure, in which an effective Lp norm is proposed to measure the sparse degree of the distinct wavelet tree nodes, is second. The ICA decomposition and reconstruction procedure, which utilises the sparse approximation coefficients set of the fMRI data, is last. The hybrid data experimental results demonstrated that the SACICA method exhibited the stronger spatial source reconstruction ability with respect to the unsmoothed fMRI data and better detection sensitivity of the functional signal on the smoothed fMRI data than the FastICA method. Furthermore, task-related experiments also revealed that SACICA was not only effective in discovering the functional networks but also exhibited a better detection sensitivity of the visual-related functional signal. In addition, the SACICA combined with Fast-FENICA proposed by Wang et al. (2012) was demonstrated to conduct the group analysis effectively on the resting-state data set.

  7. The Multisensory Attentional Consequences of Tool Use: A Functional Magnetic Resonance Imaging Study

    PubMed Central

    Holmes, Nicholas P.; Spence, Charles; Hansen, Peter C.; Mackay, Clare E.; Calvert, Gemma A.

    2008-01-01

    Background Tool use in humans requires that multisensory information is integrated across different locations, from objects seen to be distant from the hand, but felt indirectly at the hand via the tool. We tested the hypothesis that using a simple tool to perceive vibrotactile stimuli results in the enhanced processing of visual stimuli presented at the distal, functional part of the tool. Such a finding would be consistent with a shift of spatial attention to the location where the tool is used. Methodology/Principal Findings We tested this hypothesis by scanning healthy human participants' brains using functional magnetic resonance imaging, while they used a simple tool to discriminate between target vibrations, accompanied by congruent or incongruent visual distractors, on the same or opposite side to the tool. The attentional hypothesis was supported: BOLD response in occipital cortex, particularly in the right hemisphere lingual gyrus, varied significantly as a function of tool position, increasing contralaterally, and decreasing ipsilaterally to the tool. Furthermore, these modulations occurred despite the fact that participants were repeatedly instructed to ignore the visual stimuli, to respond only to the vibrotactile stimuli, and to maintain visual fixation centrally. In addition, the magnitude of multisensory (visual-vibrotactile) interactions in participants' behavioural responses significantly predicted the BOLD response in occipital cortical areas that were also modulated as a function of both visual stimulus position and tool position. Conclusions/Significance These results show that using a simple tool to locate and to perceive vibrotactile stimuli is accompanied by a shift of spatial attention to the location where the functional part of the tool is used, resulting in enhanced processing of visual stimuli at that location, and decreased processing at other locations. This was most clearly observed in the right hemisphere lingual gyrus. Such

  8. Prediction of Liver Function by Using Magnetic Resonance-based Portal Venous Perfusion Imaging

    PubMed Central

    Cao, Yue; Wang, Hesheng; Johnson, Timothy D.; Pan, Charlie; Hussain, Hero; Balter, James M.; Normolle, Daniel; Ben-Josef, Edgar; Ten Haken, Randall K.; Lawrence, Theodore S.; Feng, Mary

    2013-01-01

    Purpose To evaluate whether liver function can be assessed globally and spatially by using volumetric dynamic contrast-enhanced magnetic resonance imaging MRI (DCE-MRI) to potentially aid in adaptive treatment planning. Methods and Materials Seventeen patients with intrahepatic cancer undergoing focal radiation therapy (RT) were enrolled in institution review board-approved prospective studies to obtain DCE-MRI (to measure regional perfusion) and indocyanine green (ICG) clearance rates (to measure overall liver function) prior to, during, and at 1 and 2 months after treatment. The volumetric distribution of portal venous perfusion in the whole liver was estimated for each scan. We assessed the correlation between mean portal venous perfusion in the nontumor volume of the liver and overall liver function measured by ICG before, during, and after RT. The dose response for regional portal venous perfusion to RT was determined using a linear mixed effects model. Results There was a significant correlation between the ICG clearance rate and mean portal venous perfusion in the functioning liver parenchyma, suggesting that portal venous perfusion could be used as a surrogate for function. Reduction in regional venous perfusion 1 month after RT was predicted by the locally accumulated biologically corrected dose at the end of RT (P<.0007). Regional portal venous perfusion measured during RT was a significant predictor for regional venous perfusion assessed 1 month after RT (P<.00001). Global hypovenous perfusion pre-RT was observed in 4 patients (3 patients with hepatocellular carcinoma and cirrhosis), 3 of whom had recovered from hypoperfusion, except in the highest dose regions, post-RT. In addition, 3 patients who had normal perfusion pre-RT had marked hypervenous perfusion or reperfusion in low-dose regions post-RT. Conclusions This study suggests that MR-based volumetric hepatic perfusion imaging may be a biomarker for spatial distribution of liver function, which

  9. Towards an automated selection of spontaneous co-activity maps in functional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Sourty, Marion; Thoraval, Laurent; Roquet, Daniel; Armspach, Jean-Paul; Foucher, Jack

    2015-03-01

    Functional magnetic resonance imaging allows to assess large scale functional integration of the brain. One of the leading techniques to extract functionally relevant networks is spatial independent component analysis (ICA). Spatial ICA separates independent spatial sources, many of whom are noise or imaging artifacts, whereas some do correspond to functionally relevant Spontaneous co-Activity Maps (SAMs). For research purposes, ICA is generally performed on group data. This strategy is well adapted to uncover commonly shared networks, e.g. resting-state networks, but fails to capture idiosyncratic functional networks which may be related to pathological activity, e.g. epilepsy, hallucinations. To capture these subject specific networks, ICA has to be applied to single subjects using a large number of components, from which a tenth are SAMs. Up to now, SAMs have to be selected manually by an expert based on predefined criteria. We aim to semi-automate the selection process in order to save time. To this end, some approaches have been proposed but none with the near 100 % sensitivity required for clinical purposes. In this paper, we propose a computerized version of the SAM's criteria used by experts, based on frequential and spatial characteristics of functional networks. Here we present a pre-selection method and its results at different resolutions, with different scanners or imaging sequences. While preserving a near 100 % sensitivity, it allows an average of 70 % reduction of components to be classified which save 55% of experts' time. In comparison, group ICA fails to detect about 25% of the SAMs.

  10. Prediction of Liver Function by Using Magnetic Resonance-based Portal Venous Perfusion Imaging

    SciTech Connect

    Cao Yue; Wang Hesheng; Johnson, Timothy D.; Pan, Charlie; Hussain, Hero; Balter, James M.; Normolle, Daniel; Ben-Josef, Edgar; Ten Haken, Randall K.; Lawrence, Theodore S.; Feng, Mary

    2013-01-01

    Purpose: To evaluate whether liver function can be assessed globally and spatially by using volumetric dynamic contrast-enhanced magnetic resonance imaging MRI (DCE-MRI) to potentially aid in adaptive treatment planning. Methods and Materials: Seventeen patients with intrahepatic cancer undergoing focal radiation therapy (RT) were enrolled in institution review board-approved prospective studies to obtain DCE-MRI (to measure regional perfusion) and indocyanine green (ICG) clearance rates (to measure overall liver function) prior to, during, and at 1 and 2 months after treatment. The volumetric distribution of portal venous perfusion in the whole liver was estimated for each scan. We assessed the correlation between mean portal venous perfusion in the nontumor volume of the liver and overall liver function measured by ICG before, during, and after RT. The dose response for regional portal venous perfusion to RT was determined using a linear mixed effects model. Results: There was a significant correlation between the ICG clearance rate and mean portal venous perfusion in the functioning liver parenchyma, suggesting that portal venous perfusion could be used as a surrogate for function. Reduction in regional venous perfusion 1 month after RT was predicted by the locally accumulated biologically corrected dose at the end of RT (P<.0007). Regional portal venous perfusion measured during RT was a significant predictor for regional venous perfusion assessed 1 month after RT (P<.00001). Global hypovenous perfusion pre-RT was observed in 4 patients (3 patients with hepatocellular carcinoma and cirrhosis), 3 of whom had recovered from hypoperfusion, except in the highest dose regions, post-RT. In addition, 3 patients who had normal perfusion pre-RT had marked hypervenous perfusion or reperfusion in low-dose regions post-RT. Conclusions: This study suggests that MR-based volumetric hepatic perfusion imaging may be a biomarker for spatial distribution of liver function, which

  11. 2-Deoxy-D-Glucose Modified Magnetic Nanoparticles with Dual Functional Properties: Nanothermotherapy and Magnetic Resonance Imaging.

    PubMed

    Zhao, Lingyun; Zheng, Yajing; Yan, Hao; Xie, WenSheng; Sun, Xiaodan; Li, Ning; Tang, Jintian

    2016-03-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) with appropriate surface chemistry have attracted wild attention in medical and biological application because of their current and potential usefulness such as magnetic resonance imaging (MRI) contrast enhancement, magnetic mediated hyperthermia (MMH), immunoassay, and in drug delivery, etc. In this study, we investigated the MRI contrast agents and MMH mediators properties of the novel 2-deoxy-D-glucose (2-DG) modified SPIONs. As a non-metabolizable glucose analogue, 2-DG can block glycolysis and inhibits protein glycosylation. Moreover, SPIONs coated with 2-DG molecules can be particularly attractive to resource-hungry cancer cells, therefore to realize the targeting strategy for the SPIONs. SPIONs with amino silane as the capping agent for amino-group surface modification were synthesized by the chemical co-precipitation method with modification. Glutaraldehyde was further applied as an activation agent through which 2-DG was conjugated to the amino-coated SPIONs. Physicochemical characterizations of the 2-DG-SPIONs, such as surface morphology, surface charge and magnetic properties were investigated by Transmission Electron Microscopy (TEM), ζ-Potential and Vibrating Sample Magnetometer (VSM), etc. Magnetic inductive heating characteristics of the 2-DG-SPIONs were analyzed by exposing the SPIONs suspension (magnetic fluid) under alternative magnetic field (AMF). U-251 human glioma cells with expression of glucose transport proteins type 1 and 3 (GLUT1 and GLUT 3), and L929 murine fibroblast cell as negative control, were employed to study the effect of 2-DG modification on the cell uptake for SPIONs. TEM images for ultra-thin sections as well as ICP-MS were applied to evaluate the SPIONs internalization within the cells. In vitro MRI was performed after cells were co-incubated with SPIONs and the T2 relaxation time was measured and compared. The results demonstrate that 2-DG-SPIONs were supermagnetic and in

  12. Synthesis of citric acid functionalized magnetic graphene oxide coated corn straw for methylene blue adsorption.

    PubMed

    Ge, Heyi; Wang, Cuicui; Liu, Shanshan; Huang, Zhen

    2016-12-01

    The citric acid functionalized magnetic graphene oxide coated corn straw (CA-mGOCS) as a new adsorbent was synthesized in this work for the elimination of methylene blue (MB) from waste water. The as-prepared CA-mGOCS was tested by SEM, FTIR, XRD, Roman spectrum, TGA, particle size analyzer, BET and magnetic properties analyzer. Some factors affecting adsorption removal efficiency were explored. As a result, the addition of 5g CS (CA-mGO5CS) had the better adsorption performance than other adsorbents. The pseudo-second-order model and the Freundlich described the adsorption behavior well. The equilibrium adsorption capacity was 315.5mgg(-1) for MB at pH=12 and 298k. The electrostatic incorporation as well as hydrophobic interactions between CA-mGO5CS and MB determined the favourable adsorption property. Besides, the thermodynamic studies results ΔG<0, ΔH<0, ΔS<0 suggested that the adsorption was a spontaneous, exothermic and randomness decrease process. Finally, reusability studies imply that CA-mGO5CS has an excellent reproducibility.

  13. Fluorescence-Magnetism Functional EuS Nanocrystals with Controllable Morphologies for Dual Bioimaging.

    PubMed

    Sun, Yuanqing; Wang, Dandan; Zhao, Tianxin; Jiang, Yingnan; Zhao, Yueqi; Wang, Chuanxi; Sun, Hongchen; Yang, Bai; Lin, Quan

    2016-12-14

    Multiple functions incorporated in one single component material offer important applications in biosystems. Here we prepared a divalent state of rare earth EuS nanocrystals (NCs), which provides luminescent and magnetic properties, using both 1-Dodecanethiol (DT) and oleylamine (OLA) as reducing agents. The resultant EuS NCs exhibit controllable shapes, uniform size, and bright luminescence with a quantum yield as high as 3.5%. OLA as a surface ligand plays an important role in tunable morphologies, such as nanowires, nanorods, nanospheres et al. Another attractive nature of the EuS NCs is their paramagnetism at room temperature. In order to expand the biological applications, the resultant EuS NCs were modified with amphiphilic block copolymer F127 and transferred from oil to water phase. The excellent biocompatibility of EuS NCs is demonstrated as well as preservation of their luminescence and paramagnetic properties. The EuS NCs offer multifunction and great advantages of bright luminescence, paramagnetic, controllable morphologies, and good biocompatibility promising applications in the field of simultaneous magnetic resonance and fluorescence bioimaging.

  14. A Combined Density Functional Theory and Monte Carlo Study of Manganites for Magnetic Refrigeration

    NASA Astrophysics Data System (ADS)

    Korotana, Romi; Mallia, Giuseppe; Gercsi, Zsolt; Harrison, Nicholas

    2015-03-01

    Perovskite oxides are considered to be strong candidates for applications in magnetic refrigeration technology, due to their remarkable properties, in addition to low processing costs. Manganites with the general formula R1-xAxMnO3, particularly for A=Ca and 0 . 2 < x < 0 . 5 , undergo a field driven transition from a paramagnetic to ferromagnetic state, which is accompanied by changes in the lattice and electronic structure. Therefore, one may anticipate a large entropy change across the phase transition due to the first order nature. The present work aims to achieve an understanding of the relevant structural, magnetic, and electronic entropy contributions in the doped compound La0.75Ca0.25MnO3. A combination of thermodynamics and first principles theory is applied to determine individual contributions to the total entropy change of the system. Hybrid-exchange density functional (B3LYP) calculations for La0.75Ca0.25MnO3 predict an anti-Jahn-Teller polaron in the localised hole state, which is influenced by long-range cooperative Jahn-Teller distortions. Through the analysis of individual entropy contributions, it is identified that the electronic and vibrational terms have a deleterious effect on the total entropy change.

  15. Study on the adsorption of Cu(II) by folic acid functionalized magnetic graphene oxide

    NASA Astrophysics Data System (ADS)

    Wang, Cuicui; Ge, Heyi; Zhao, Yueying; Liu, Shanshan; Zou, Yu; Zhang, Wenbo

    2017-02-01

    The folic acid functionalized magnetic graphene oxide (FA-mGO) as a new adsorbent has been synthesized in this work for the elimination of Cu(II) from waste water. The as-prepared FA-mGO was tested by SEM, TEM, particle size analyzer, FTIR, XRD, Roman spectrum, TGA and magnetic properties analyzer. Some factors, such as adsorbent dose, pH, contact time, initial concentration of adsorbate and temperature were explored. The results showed that the FA-mGO had the better adsorption performance than mGO. After 40 min, the adsorption equilibrium could be reached. Furthermore, the adsorption property obeyed the pseudo-second order kinetic model and the Temkin isotherms well. The maximum adsorption capacity was 283.29 mg/g for Cu(II) from Pseudo-second-order model at pH=5 and 318 K. The chelation action between FA and Cu(II) along with electrostatic incorporation between GO and Cu(II) determined the favourable adsorption property. Besides, thermodynamic studies results ∆G0<0, ∆H0>0, ∆S0>0 suggested that the adsorption mechanism was an endothermic and spontaneous process essentially. Finally, desorption and reusability studies imply FA-mGO has an excellent reproducibility and is benefit to environmental protection and resource conservation.

  16. Measuring Pain for Patients Seeking Physical Therapy: Can Functional Magnetic Resonance Imaging (fMRI) Help?

    PubMed

    Elliott, James M; Owen, Meriel; Bishop, Mark D; Sparks, Cheryl; Tsao, Henry; Walton, David M; Weber, Kenneth A; Wideman, Timothy H

    2016-07-28

    In the multidisciplinary fields of pain medicine and rehabilitation, advancing techniques such as functional magnetic resonance imaging (fMRI) are used to enhance our understanding of the pain experience. Given that such measures, in some circles, are expected to help us understand the brain in pain, future research in pain measurement is undeniably rich with possibility. However, pain remains intensely personal and represents a multifaceted experience, unique to each individual; no single measure in isolation, fMRI included, can prove or quantify its magnitude beyond the patient self-report. Physical therapists should be aware of cutting-edge advances in measuring the patient's pain experience, and they should work closely with professionals in other disciplines (eg, magnetic resonance physicists, biomedical engineers, radiologists, psychologists) to guide the exploration and development of multimodal pain measurement and management on a patient-by-patient basis. The primary purpose of this perspective article is to provide a brief overview of fMRI and inform physical therapist clinicians of the pros and cons when utilized as a measure of the patient's perception of pain. A secondary purpose is to describe current known factors that influence the quality of fMRI data and its analyses, as well as the potential for future clinical applications relevant to physical therapist practice. Lastly, the interested reader is introduced and referred to existing guidelines and recommendations for reporting fMRI research.

  17. Neural Alterations in Acquired Age-Related Hearing Loss.

    PubMed

    Mudar, Raksha A; Husain, Fatima T

    2016-01-01

    Hearing loss is one of the most prevalent chronic health conditions in older adults. Growing evidence suggests that hearing loss is associated with reduced cognitive functioning and incident dementia. In this mini-review, we briefly examine literature on anatomical and functional alterations in the brains of adults with acquired age-associated hearing loss, which may underlie the cognitive consequences observed in this population, focusing on studies that have used structural and functional magnetic resonance imaging, diffusion tensor imaging, and event-related electroencephalography. We discuss structural and functional alterations observed in the temporal and frontal cortices and the limbic system. These neural alterations are discussed in the context of common cause, information-degradation, and sensory-deprivation hypotheses, and we suggest possible rehabilitation strategies. Although, we are beginning to learn more about changes in neural architecture and functionality related to age-associated hearing loss, much work remains to be done. Understanding the neural alterations will provide objective markers for early identification of neural consequences of age-associated hearing loss and for evaluating benefits of intervention approaches.

  18. Love-related changes in the brain: a resting-state functional magnetic resonance imaging study.

    PubMed

    Song, Hongwen; Zou, Zhiling; Kou, Juan; Liu, Yang; Yang, Lizhuang; Zilverstand, Anna; d'Oleire Uquillas, Federico; Zhang, Xiaochu

    2015-01-01

    Romantic love is a motivational state associated with a desire to enter or maintain a close relationship with a specific other person. Functional magnetic resonance imaging (fMRI) studies have found activation increases in brain regions involved in the processing of reward, motivation and emotion regulation, when romantic lovers view photographs of their partners. However, not much is known about whether romantic love affects the brain's functional architecture during rest. In the present study, resting state functional magnetic resonance imaging (rsfMRI) data was collected to compare the regional homogeneity (ReHo) and functional connectivity (FC) across an "in-love" group (LG, N = 34, currently intensely in love), an "ended-love" group (ELG, N = 34, ended romantic relationship recently), and a "single" group (SG, N = 32, never fallen in love). Results show that: (1) ReHo of the left dorsal anterior cingulate cortex (dACC) was significantly increased in the LG (in comparison to the ELG and the SG); (2) ReHo of the left dACC was positively correlated with length of time in love in the LG, and negatively correlated with the lovelorn duration since breakup in the ELG; (3) FC within the reward, motivation, and emotion regulation network (dACC, insula, caudate, amygdala, and nucleus accumbens) as well as FC in the social cognition network [temporo-parietal junction (TPJ), posterior cingulate cortex (PCC), medial prefrontal cortex (MPFC), inferior parietal, precuneus, and temporal lobe] was significantly increased in the LG (in comparison to the ELG and SG); (4) in most regions within both networks FC was positively correlated with the duration of love in the LG but negatively correlated with the lovelorn duration of time since breakup in the ELG. This study provides first empirical evidence of love-related alterations in brain functional architecture. Furthermore, the results shed light on the underlying neural mechanisms of romantic love, and demonstrate the

  19. Love-related changes in the brain: a resting-state functional magnetic resonance imaging study

    PubMed Central

    Song, Hongwen; Zou, Zhiling; Kou, Juan; Liu, Yang; Yang, Lizhuang; Zilverstand, Anna; d’Oleire Uquillas, Federico; Zhang, Xiaochu

    2015-01-01

    Romantic love is a motivational state associated with a desire to enter or maintain a close relationship with a specific other person. Functional magnetic resonance imaging (fMRI) studies have found activation increases in brain regions involved in the processing of reward, motivation and emotion regulation, when romantic lovers view photographs of their partners. However, not much is known about whether romantic love affects the brain’s functional architecture during rest. In the present study, resting state functional magnetic resonance imaging (rsfMRI) data was collected to compare the regional homogeneity (ReHo) and functional connectivity (FC) across an “in-love” group (LG, N = 34, currently intensely in love), an “ended-love” group (ELG, N = 34, ended romantic relationship recently), and a “single” group (SG, N = 32, never fallen in love). Results show that: (1) ReHo of the left dorsal anterior cingulate cortex (dACC) was significantly increased in the LG (in comparison to the ELG and the SG); (2) ReHo of the left dACC was positively correlated with length of time in love in the LG, and negatively correlated with the lovelorn duration since breakup in the ELG; (3) FC within the reward, motivation, and emotion regulation network (dACC, insula, caudate, amygdala, and nucleus accumbens) as well as FC in the social cognition network [temporo-parietal junction (TPJ), posterior cingulate cortex (PCC), medial prefrontal cortex (MPFC), inferior parietal, precuneus, and temporal lobe] was significantly increased in the LG (in comparison to the ELG and SG); (4) in most regions within both networks FC was positively correlated with the duration of love in the LG but negatively correlated with the lovelorn duration of time since breakup in the ELG. This study provides first empirical evidence of love-related alterations in brain functional architecture. Furthermore, the results shed light on the underlying neural mechanisms of romantic love, and demonstrate

  20. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  1. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  2. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  3. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  4. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  5. The effect of musical training on music processing: a functional magnetic resonance imaging study in humans.

    PubMed

    Schmithorst, Vincent J; Holland, Scott K

    2003-09-11

    Previous studies have demonstrated changes in neuronal activity in trained musicians relative to controls while performing various music processing tasks. In this study the neural correlates of the effect of music training on two aspects of music processing, melody and harmony, are investigated using functional magnetic resonance imaging (fMRI). Fifteen subjects, seven with continuous musical training from early childhood to adulthood and eight without, underwent a passive fMRI listening paradigm designed to test the effects of melodic and harmonic processing. Melodic processing activated the most anterior part of the superior temporal gyrus for both musicians and non-musicians, while harmonic processing activated different visual association areas for musicians relative to non-musicians. The inferior parietal lobules were recruited only by musicians for both tasks. We conclude that musical training results in the recruitment of different neural networks for these aspects of music processing.

  6. Functionalized magnetic microparticle-based colorimetric platform for influenza A virus detection

    NASA Astrophysics Data System (ADS)

    Chen, Chaohui; Zou, Zhong; Chen, Lu; Ji, Xinghu; He, Zhike

    2016-10-01

    A colorimetric platform for influenza A virus detection was developed by using the high efficiency of enzymatic catalysis and the reduction of gold ions with hydrogen peroxide. Aptamer-functionalized magnetic microparticles were synthesized to capture the influenza A virus. This was followed by the binding of ConA-GOx-AuNPs to the H3N2 virus through the ConA-glycan interaction. The sandwich complex was subsequently dispersed in glucose solution to trigger an enzymatic reaction to produce hydrogen peroxide, which controlled the growth of gold nanoparticles and produced colored solutions. The determination of H3N2 concentration was realized by comparing the two differently colored gold nanoparticles. This method could detect the target virus as low as 11.16 μg ml-1. Furthermore, it opens new opportunities for sensitive and colorimetric detection of viruses and proteins.

  7. Somatotopical relationships between cortical activity and reflex areas in reflexology: a functional magnetic resonance imaging study.

    PubMed

    Nakamaru, Tomomi; Miura, Naoki; Fukushima, Ai; Kawashima, Ryuta

    2008-12-19

    We examined the somatotopical relationship between cortical activity and sensory stimulation of reflex areas in reflexology using functional magnetic resonance imaging. Three reflex areas on the left foot, relating to the eye, shoulder, and small intestine were stimulated during the experiment. A statistical analysis showed that reflexological stimulation of the foot reflex areas corresponding to the eye, shoulder, and small intestine activated not only the somatosensory areas corresponding to the foot, but also the somatosensory areas corresponding to the eye, shoulder, and small intestine or neighboring body parts. Thus, the findings showed that reflexological stimulation induced a somatosensory process corresponding to the stimulated reflex area and that a neuroimaging approach can be used to examine the basis of reflexology effects.

  8. Mapping brain region activity during chewing: a functional magnetic resonance imaging study.

    PubMed

    Onozuka, M; Fujita, M; Watanabe, K; Hirano, Y; Niwa, M; Nishiyama, K; Saito, S

    2002-11-01

    Mastication has been suggested to increase neuronal activities in various regions of the human brain. However, because of technical difficulties, the fine anatomical and physiological regions linked to mastication have not been fully elucidated. Using functional magnetic resonance imaging during cycles of rhythmic gum-chewing and no chewing, we therefore examined the interaction between chewing and brain regional activity in 17 subjects (aged 20-31 years). In all subjects, chewing resulted in a bilateral increase in blood oxygenation level-dependent (BOLD) signals in the sensorimotor cortex, supplementary motor area, insula, thalamus, and cerebellum. In addition, in the first three regions, chewing of moderately hard gum produced stronger BOLD signals than the chewing of hard gum. However, the signal was higher in the cerebellum and not significant in the thalamus, respectively. These results suggest that chewing causes regional increases in brain neuronal activities which are related to biting force.

  9. Functional Neurosurgery in the Human Thalamus by Transcranial Magnetic Resonance Guided Focused Ultrasound

    NASA Astrophysics Data System (ADS)

    Werner, Beat; Morel, Anne; Jeanmonod, Daniel; Martin, Ernst

    2009-04-01

    Potential applications of Transcranial Magnetic Resonance guided Focused Ultrasound (TcMRgFUS) include treatment of functional brain disorders, such as Parkinson's disease, dystonia and tremor, neurogenic pain and tinnitus, neuropsychiatric disorders and epilepsy. In this study we demonstrate the feasibility of non-invasive TcMRgFUS ablation of clinically well established targets in the human thalamus that are currently accessed stereotactically by interventional strategies based on the concept of the thalamocortical dysrhythmia (TCD). Thermal hotspots suitable for clinical intervention were created successfully in anatomical preparations of human ex-vivo heads under pseudo clinical conditions. The hotspots could be positioned at the target locations as needed and local energy deposition was sufficient to create tissue ablation. Numerical simulations based on these experimental data predict that the acoustic energy needed to create ablative lesions in-vivo will be within limits that can safely applied.

  10. "More is different" in functional magnetic resonance imaging: a review of recent data analysis techniques.

    PubMed

    Lohmann, Gabriele; Stelzer, Johannes; Neumann, Jane; Ay, Nihat; Turner, Robert

    2013-01-01

    Two aspects play a key role in recently developed strategies for functional magnetic resonance imaging (fMRI) data analysis: first, it is now recognized that the human brain is a complex adaptive system and exhibits the hallmarks of complexity such as emergence of patterns arising out of a multitude of interactions between its many constituents. Second, the field of fMRI has evolved into a data-intensive, big data endeavor with large databases and masses of data being shared around the world. At the same time, ultra-high field MRI scanners are now available producing data at previously unobtainable quality and quantity. Both aspects have led to shifts in the way in which we view fMRI data. Here, we review recent developments in fMRI data analysis methodology that resulted from these shifts in paradigm.

  11. Electron Energy Distribution function in a weakly magnetized expanding helicon plasma discharge

    NASA Astrophysics Data System (ADS)

    Sirse, Nishant; Harvey, Cleo; Gaman, Cezar; Ellingboe, Bert

    2016-09-01

    Helicon wave heating is well known to produce high-density plasma source for application in plasma thrusters, plasma processing and many more. Our previous study (B Ellingboe et al. APS Gaseous Electronics Conference 2015, abstract #KW2.005) has shown observation of helicon wave in a weakly magnetized inductively coupled plasma source excited by m =0 antenna at 13.56 MHz. In this paper, we investigated the Electron Energy Distribution Function (EEDF) in the same setup by using an RF compensated Langmuir probe. The ac signal superimposition technique (second harmonic technique) is used to determine EEDF. The EEDF is measured for 5-100 mTorr gas pressure, 100 W - 1.5 kW rf power and at different locations in the source chamber, boundary and diffusion chamber. This paper will discuss the change in the shape of EEDF for various heating mode transitions.

  12. 2D crack problems in functionally graded magnet-electro-elastic materials

    NASA Astrophysics Data System (ADS)

    Stoynov, Yonko

    2016-12-01

    Magneto-electro-elastic composite materials have extensive application in modern smart structures, because they possess good coupling between mechanical, electrical and magnetic fields. This new effect was reported for the first time by Van Suchtelen [1] in 1972. Due to their ceramic structure cracks inevitably exists in these materials. In this study we consider functionally graded magneto-electro-elastic materials subjected to anti-plane time harmonic load. We use Boundary integral equation method (BIEM) to evaluate the dependence of stress concentration near the crack tip on the frequency of the applied external load. For complex crack configurations numerical calculations are tedious and need too much time. Here we present a new analytical approach that will significantly improve the numerical procedure for calculation of stress intensity factors (SIF).

  13. Energy distribution functions of kilovolt ions parallel and perpendicular to the magnetic field of a modified Penning discharge

    NASA Technical Reports Server (NTRS)

    Roth, R. J.

    1973-01-01

    The distribution function of ion energy parallel to the magnetic field of a modified Penning discharge has been measured with a retarding potential energy analyzer. These ions escaped through one of the throats of the magnetic mirror geometry. Simultaneous measurements of the ion energy distribution function perpendicular to the magnetic field have been made with a charge exchange neutral detector. The ion energy distribution functions are approximately Maxwellian, and the parallel and perpendicular kinetic temperatures are equal within experimental error. These results suggest that turbulent processes previously observed in this discharge Maxwellianize the velocity distribution along a radius in velocity space and cause an isotropic energy distribution. When the distributions depart from Maxwellian, they are enhanced above the Maxwellian tail.

  14. Nuisance Regression of High-Frequency Functional Magnetic Resonance Imaging Data: Denoising Can Be Noisy.

    PubMed

    Chen, Jingyuan E; Jahanian, Hesamoddin; Glover, Gary H

    2017-02-01

    Recently, emerging studies have demonstrated the existence of brain resting-state spontaneous activity at frequencies higher than the conventional 0.1 Hz. A few groups utilizing accelerated acquisitions have reported persisting signals beyond 1 Hz, which seems too high to be accommodated by the sluggish hemodynamic process underpinning blood oxygen level-dependent contrasts (the upper limit of the canonical model is ∼0.3 Hz). It is thus questionable whether the observed high-frequency (HF) functional connectivity originates from alternative mechanisms (e.g., inflow effects, proton density changes in or near activated neural tissue) or rather is artificially introduced by improper preprocessing operations. In this study, we examined the influence of a common preprocessing step-whole-band linear nuisance regression (WB-LNR)-on resting-state functional connectivity (RSFC) and demonstrated through both simulation and analysis of real dataset that WB-LNR can introduce spurious network structures into the HF bands of functional magnetic resonance imaging (fMRI) signals. Findings of present study call into question whether published observations on HF-RSFC are partly attributable to improper data preprocessing instead of actual neural activities.

  15. Neural correlates of attachment trauma in borderline personality disorder: a functional magnetic resonance imaging study.

    PubMed

    Buchheim, Anna; Erk, Susanne; George, Carol; Kächele, Horst; Kircher, Tilo; Martius, Philipp; Pokorny, Dan; Ruchsow, Martin; Spitzer, Manfred; Walter, Henrik

    2008-08-30

    Functional imaging studies have shown that individuals with borderline personality disorder (BPD) display prefrontal and amygdala dysfunction while viewing or listening to emotional or traumatic stimuli. The study examined for the first time the functional neuroanatomy of attachment trauma in BPD patients using functional magnetic resonance imaging (fMRI) during the telling of individual stories. A group of 11 female BPD patients and 17 healthy female controls, matched for age and education, told stories in response to a validated set of seven attachment pictures while being scanned. Group differences in narrative and neural responses to "monadic" pictures (characters facing attachment threats alone) and "dyadic" pictures (interaction between characters in an attachment context) were analyzed. Behavioral narrative data showed that monadic pictures were significantly more traumatic for BPD patients than for controls. As hypothesized BPD patients showed significantly more anterior midcingulate cortex activation in response to monadic pictures than controls. In response to dyadic pictures patients showed more activation of the right superior temporal sulcus and less activation of the right parahippocampal gyrus compared to controls. Our results suggest evidence for potential neural mechanisms of attachment trauma underlying interpersonal symptoms of BPD, i.e. fearful and painful intolerance of aloneness, hypersensitivity to social environment, and reduced positive memories of dyadic interactions.

  16. Computer-controlled stimulation for functional magnetic resonance imaging studies of the neonatal olfactory system

    PubMed Central

    Arichi, T; Gordon-Williams, R; Allievi, A; Groves, AM; Burdet, E; Edwards, AD

    2013-01-01

    Aim Olfactory sensation is highly functional early in human neonatal life, with studies suggesting that odours can influence behaviour and infant–mother bonding. Due to its good spatial properties, blood oxygen level–dependent (BOLD) contrast functional magnetic resonance imaging (fMRI) has the potential to rapidly advance our understanding of the neural activity which underlies the development of olfactory perception in this key period. We aimed to design an ‘olfactometer’ specifically for use with neonatal subjects for fMRI studies of odour perception. Methods We describe a fully automated and programmable, fMRI compatible system capable of presenting odorant liquids. To prevent contamination of the system and minimize between-subject infective risk, the majority of the olfactometer is constructed from single-use, readily available clinical equipment. The system was used to present the odour of infant formula milk in a validation group of seven neonatal subjects at term equivalent postmenstrual age (median age 40 weeks). Results A safe, reliable and reproducible pattern of stimulation was delivered leading to well-localized positive BOLD functional responses in the piriform cortex, amygdala, thalamus, insular cortex and cerebellum. Conclusions The described system is therefore suitable for detailed studies of the ontology of olfactory sensation and perception during early human brain development. PMID:23789919

  17. Using functional magnetic resonance imaging and electroencephalography to detect consciousness after severe brain injury.

    PubMed

    Owen, Adrian M

    2015-01-01

    In recent years, rapid technological developments in the field of neuroimaging have provided new methods for revealing thoughts, actions, and intentions based solely on the pattern of activity that is observed in the brain. In specialized centres, these methods are now being employed routinely in the assessment of patients diagnosed with so-called "disorders of consciousness," mapping patterns of residual function and dysfunction and helping to reduce diagnostic errors between related conditions such as the vegetative and minimally conscious states. Both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) have now been shown to be effective tools for detecting covert awareness in behaviorally nonresponsive patients when standard clinical approaches have been unable to provide that information. Indeed, in some patients, communication with the outside world via simple "yes" and "no" questions has been achieved, even in cases where no possibility for behavioral interaction exists. These studies have profound implications for clinical care, diagnosis, prognosis and medical-legal decision making relating to the prolongation, or otherwise, of life after severe brain injury. Moreover, the results suggest an urgent need for a re-evaluation of the existing diagnostic guidelines for behaviorally nonresponsive patients to include information derived from functional neuroimaging.

  18. The effect of magnetic resonance imaging noise on cochlear function in dogs.

    PubMed

    Venn, R E; McBrearty, A R; McKeegan, D; Penderis, J

    2014-10-01

    Noise produced by magnetic resonance imaging (MRI) scanners (which can peak at a sound pressure level of 131 dB) has been shown to cause noise-induced cochlear dysfunction in people. The aim of this study was to investigate whether noise produced during MRI had a deleterious effect on cochlear function in dogs, using distortion product otoacoustic emission (DPOAE) testing, which allows frequency specific, non-invasive assessment of cochlear function. DPOAE testing was performed before and after MRI in one or both ears under general anaesthesia at 14 frequency pairs (f2 frequency ranging from 0.84 kHz to 8.0 kHz). A control group comprised dogs undergoing anaesthesia of a similar duration for quiet procedures. Thirty-six dogs (66 ears) and 17 dogs (28 ears) were included in the MRI and control groups respectively. There was a reduction in DPOAE at all frequencies tested in the MRI group; a similar effect was not evident in the control group. This reduction in the MRI group was statistically significant in five of the 14 frequencies assessed (P < 0.05). These results demonstrate that exposure to MRI noise results in a significant reduction in frequency-specific cochlear function in dogs, although it is not known whether this is reversible or permanent. This suggests that all dogs undergoing MRI studies should be provided with ear protection as a routine precautionary measure.

  19. Cognitive functioning and deep transcranial magnetic stimulation (DTMS) in major psychiatric disorders: A systematic review.

    PubMed

    Kedzior, Karina Karolina; Gierke, Lioba; Gellersen, Helena Marie; Berlim, Marcelo T

    2016-04-01

    Deep transcranial magnetic stimulation (DTMS) is a non-invasive brain stimulation method mostly utilised in the treatment of major depression. The aim of the current study was to systematically review the literature on the cognitive effects of DTMS applied with the H-coil system in major psychiatric disorders. Following a literature search in PsycInfo and PubMed (any time to December 2015), 13 out of 32 studies on DTMS and cognitive functioning were included in the current review. Three studies included 38 healthy participants, eight studies included 158 unipolar or bipolar depression patients and two studies included 45 schizophrenia patients. Low-frequency DTMS (1-3 sessions) had little effect on cognitive functioning in healthy participants. The most consistent cognitive and clinical improvements were reported in the short-term (after 20 daily sessions of high-frequency DTMS with H1-coil) in studies with major depression patients. There was also a trend towards a short-term cognitive and clinical improvement in studies with schizophrenia patients. High-frequency DTMS might improve cognitive functioning and alleviate clinical symptoms in the short-term, particularly in major depression. However, this conclusion is based on data from mostly uncontrolled, open-label studies with patients receiving concurrent antidepressants or antipsychotics. Randomised, sham-controlled trials are needed to investigate the magnitude of the cognitive outcomes of DTMS in the short-term and beyond the daily stimulation phase in major psychiatric disorders.

  20. Assessment of allograft function using diffusion-weighted magnetic resonance imaging in kidney transplant patients.

    PubMed

    Kaul, Anupma; Sharma, Raj Kumar; Gupta, Rakesh Kumar; Lal, Hira; Yadav, Abhishek; Bhadhuria, Dharmendra; Prasad, Narayan; Gupta, Amit

    2014-11-01

    Developing a non-invasive method such as diffusion-weighted magnetic resonance imaging (DWMRI) could be used as a feasible and reproducible modality in the differential diagnosis of allograft dysfunction. We assessed the functional status of the renal allograft by DWMRI and its applicability in assessment of graft dysfunction on all end-stage renal transplant patients who attained normal renal function on the 7th day post-transplantation. Follow-up imaging of the recipient allograft was performed at the end of 90 and 180 days and in case of graft dysfunction. Kidney biopsies were performed to correlate with the corresponding MRI. The apparent diffusion coefficient (ADC) maps of the cortex and medulla were obtained by studying the DWMRI. The ADC values were significantly lower in the medulla compared with the cortex in normal donor kidneys and normally functioning transplanted kidneys, while they decreased significantly when rejection occurred. The reduction in ADC values occurred both in the cortex and in the medulla, and correlated with the degree of rejection on the kidney biopsies. The ADC values increased significantly during the recovery from rejection. We conclude that DWMRI can be beneficial in the diagnosis and follow-up of transplant patients during acute rejection.

  1. Alterations in vascular function in primary aldosteronism: a cardiovascular magnetic resonance imaging study.

    PubMed

    Mark, P B; Boyle, S; Zimmerli, L U; McQuarrie, E P; Delles, C; Freel, E M

    2014-02-01

    Excess aldosterone is associated with increased cardiovascular risk. Aldosterone has a permissive effect on vascular fibrosis. Cardiovascular magnetic resonance imaging (CMR) allows study of vascular function by measuring aortic distensibility. We compared aortic distensibility in primary aldosteronism (PA), essential hypertension (EH) and normal controls and explored the relationship between aortic distensibility and pulse wave velocity (PWV). We studied PA (n=14) and EH (n=33) subjects and age-matched healthy controls (n=17) with CMR, including measurement of aortic distensibility, and measured PWV using applanation tonometry. At recruitment, PA and EH patients had similar blood pressure and left ventricular mass. Subjects with PA had significantly lower aortic distensibility and higher PWV compared with EH and healthy controls. These changes were independent of other factors associated with reduced aortic distensibility, including ageing. There was a significant relationship between increasing aortic stiffness and age in keeping with physical and vascular ageing. As expected, aortic distensibility and PWV were closely correlated. These results demonstrate that PA patients display increased arterial stiffness compared with EH, independent of vascular ageing. The implication is that aldosterone invokes functional impairment of arterial function. The long-term implications of arterial stiffening in aldosterone excess require further study.

  2. The neural basis of the blood-oxygen-level-dependent functional magnetic resonance imaging signal.

    PubMed Central

    Logothetis, Nikos K

    2002-01-01

    Magnetic resonance imaging (MRI) has rapidly become an important tool in clinical medicine and biological research. Its functional variant (functional magnetic resonance imaging; fMRI) is currently the most widely used method for brain mapping and studying the neural basis of human cognition. While the method is widespread, there is insufficient knowledge of the physiological basis of the fMRI signal to interpret the data confidently with respect to neural activity. This paper reviews the basic principles of MRI and fMRI, and subsequently discusses in some detail the relationship between the blood-oxygen-level-dependent (BOLD) fMRI signal and the neural activity elicited during sensory stimulation. To examine this relationship, we conducted the first simultaneous intracortical recordings of neural signals and BOLD responses. Depending on the temporal characteristics of the stimulus, a moderate to strong correlation was found between the neural activity measured with microelectrodes and the BOLD signal averaged over a small area around the microelectrode tips. However, the BOLD signal had significantly higher variability than the neural activity, indicating that human fMRI combined with traditional statistical methods underestimates the reliability of the neuronal activity. To understand the relative contribution of several types of neuronal signals to the haemodynamic response, we compared local field potentials (LFPs), single- and multi-unit activity (MUA) with high spatio-temporal fMRI responses recorded simultaneously in monkey visual cortex. At recording sites characterized by transient responses, only the LFP signal was significantly correlated with the haemodynamic response. Furthermore, the LFPs had the largest magnitude signal and linear systems analysis showed that the LFPs were better than the MUAs at predicting the fMRI responses. These findings, together with an analysis of the neural signals, indicate that the BOLD signal primarily measures the input

  3. Multi-functional liposomes showing radiofrequency-triggered release and magnetic resonance imaging for tumor multi-mechanism therapy

    NASA Astrophysics Data System (ADS)

    Du, Bin; Han, Shuping; Li, Hongyan; Zhao, Feifei; Su, Xiangjie; Cao, Xiaohui; Zhang, Zhenzhong

    2015-03-01

    Recently, nanoplatforms with multiple functions, such as tumor-targeting drug carriers, MRI, optical imaging, thermal therapy etc., have become popular in the field of cancer research. The present study reports a novel multi-functional liposome for cancer theranostics. A dual targeted drug delivery with radiofrequency-triggered drug release and imaging based on the magnetic field influence was used advantageously for tumor multi-mechanism therapy. In this system, the surface of fullerene (C60) was decorated with iron oxide nanoparticles, and PEGylation formed a hybrid nanosystem (C60-Fe3O4-PEG2000). Thermosensitive liposomes (dipalmitoylphosphatidylcholine, DPPC) with DSPE-PEG2000-folate wrapped up the hybrid nanosystem and docetaxel (DTX), which were designed to combine features of biological and physical (magnetic) drug targeting for fullerene radiofrequency-triggered drug release. The magnetic liposomes not only served as powerful tumor diagnostic magnetic resonance imaging (MRI) contrast agents, but also as powerful agents for photothermal ablation of tumors. Furthermore, a remarkable thermal therapy combined chemotherapy multi-functional liposome nanoplatform converted radiofrequency energy into thermal energy to release drugs from thermosensitive liposomes, which was also observed during both in vitro and in vivo treatment. The multi-functional liposomes also could selectively kill cancer cells in highly localized regions via their excellent active tumor targeting and magnetic targeted abilities.

  4. Numerical and exact density functional studies of light atoms in strong magnetic fields

    NASA Astrophysics Data System (ADS)

    Zhu, Wuming

    2005-11-01

    Although current density functional theory (CDFT) was proposed almost two decades ago, rather little progress has been made in development and application of this theory, in contrast to many successful applications that ordinary density functional theory (DFT) has enjoyed. In parallel with early DFT exploration, we have made extensive studies on atom-like systems in an external magnetic field. The objectives are to advance our comparative understanding of the DFT and CDFT descriptions of such systems. A subsidiary objective is to provide extensive data on light atoms in high fields, notably those of astrophysical interest. To address the cylindrical symmetry induced by the external field, an efficient, systematic way to construct high quality basis sets within anisotropic Gaussians is provided. Using such basis sets, we did extensive Hartree-Fock and DFT calculations on helium through carbon atoms in a wide range of B fields. The applicability and limitations of modern DFT and CDFT functionals for atomic systems in such fields is analyzed. An exact soluble two-electron model system, Hooke's atom (HA), is studied in detail. Analogously with known results for zero field, we developed exact analytical solutions for some specific confinement and field strengths. Exact DFT and CDFT quantities for the HA in B fields, specifically exchange and correlation functionals were obtained and compared with results from approximate functionals. Major qualitative differences were identified. A major overall conclusion of the work is that the vorticity variable, introduced in CDFT to ensure gauge invariance, is rather difficult to handle computationally. The difficulty is severe enough to suggest that it might be profitable to seek an alternative gauge-invariance formulation of the current-dependence in DFT.

  5. Nonuniqueness of magnetic fields and energy derivatives in spin-polarized density functional theory.

    PubMed

    Gál, T; Ayers, P W; De Proft, F; Geerlings, P

    2009-10-21

    The effect of the recently uncovered nonuniqueness of the external magnetic field B(r) corresponding to a given pair of density n(r) and spin density n(s)(r) on the derivative of the energy functional of spin-polarized density functional theory, and its implications for the definition of chemical reactivity descriptors, is examined. For ground states, the nonuniqueness of B(r) implies the nondifferentiability of the energy functional E(v,B)[n,n(s)] with respect to n(s)(r). It is shown, on the other hand, that this nonuniqueness allows the existence of the one-sided derivatives of E(v,B)[n,n(s)] with respect to n(s)(r). Although the N-electron ground state can always be obtained from the minimization of E(v,B)[n,n(s)] without any constraint on the spin number N(s)=integraln(s)(r)dr, the Lagrange multiplier mu(s) associated with the fixation of N(s) does not vanish even for ground states. Mu(s) is identified as the left- or right-side derivative of the total energy with respect to N(s), which justifies the interpretation of mu(s) as a (spin) chemical potential. This is relevant not only for the spin-polarized generalization of conceptual density functional theory, the spin chemical potential being one of the elementary reactivity descriptors, but also for the extension of the thermodynamical analogy of density functional theory for the spin-polarized case. For higher-order reactivity indices, B(r)'s nonuniqueness has similar implications as for mu(s), leading to a split of the indices with respect to N(s) into one-sided reactivity descriptors.

  6. The magnetic and electronic structure of vanadyl pyrophosphate from density functional theory

    SciTech Connect

    Cheng, Mu-Jeng; Nielsen, Robert J.; Tahir-Kheli, Jamil; Goddard III, William A.

    2011-01-01

    We have studied the magnetic structure of the high symmetry vanadyl pyrophosphate ((VO)₂P₂O₇, VOPO), focusing on the spin exchange couplings, using density functional theory (B3LYP) with the full three-dimensional periodicity. VOPO involves four distinct spin couplings: two larger couplings exist along the chain direction (a-axis), which we predict to be antiferromagnetic, JOPO = ₋156.8 K and JO = ₋68.6 K, and two weaker couplings appear along the c (between two layers) and b directions (between two chains in the same layer), which we calculate to be ferromagnetic, Jlayer = 19.2 K and Jchain = 2.8 K. Based on the local density of states and the response of spin couplings to varying the cell parameter a, we found that JOPO originates from a super-exchange interaction through the bridging –O–P–O– unit. In contrast, JO results from a direct overlap of 3dx²₋y² orbitals on two vanadium atoms in the same V2O8 motif, making it very sensitive to structural fluctuations. Based on the variations in V–O bond length as a function of strain along a, we found that the V–O bonds of V–(OPO)2–V are covalent and rigid, whereas the bonds of V–(O)2–V are fragile and dative. These distinctions suggest that compression along the a-axis would have a dramatic impact on JO, changing the magnetic structure and spin gap of VOPO. This result also suggests that assuming JO to be a constant over the range of 2–300 K whilst fitting couplings to the experimental magnetic susceptibility is an invalid method. Regarding its role as a catalyst, the bonding pattern suggests that O2 can penetrate beyond the top layers of the VOPO surface, converting multiple V atoms from the +4 to +5 oxidation state, which seems crucial to explain the deep oxidation of n-butane to maleic anhydride.

  7. Evidence of cortical reorganization of language networks after stroke with subacute Broca's aphasia: a blood oxygenation level dependent-functional magnetic resonance imaging study

    PubMed Central

    Qiu, Wei-hong; Wu, Hui-xiang; Yang, Qing-lu; Kang, Zhuang; Chen, Zhao-cong; Li, Kui; Qiu, Guo-rong; Xie, Chun-qing; Wan, Gui-fang; Chen, Shao-qiong

    2017-01-01

    Aphasia is an acquired language disorder that is a common consequence of stroke. The pathogenesis of the disease is not fully understood, and as a result, current treatment options are not satisfactory. Here, we used blood oxygenation level-dependent functional magnetic resonance imaging to evaluate the activation of bilateral cortices in patients with Broca's aphasia 1 to 3 months after stroke. Our results showed that language expression was associated with multiple brain regions in which the right hemisphere participated in the generation of language. The activation areas in the left hemisphere of aphasia patients were significantly smaller compared with those in healthy adults. The activation frequency, volumes, and intensity in the regions related to language, such as the left inferior frontal gyrus (Broca's area), the left superior temporal gyrus, and the right inferior frontal gyrus (the mirror region of Broca's area), were lower in patients compared with healthy adults. In contrast, activation in the right superior temporal gyrus, the bilateral superior parietal lobule, and the left inferior temporal gyrus was stronger in patients compared with healthy controls. These results suggest that the right inferior frontal gyrus plays a role in the recovery of language function in the subacute stage of stroke-related aphasia by increasing the engagement of related brain areas. PMID:28250756

  8. The Effect of Disruption of Prefrontal Cortical Function with Transcranial Magnetic Stimulation on Visual Working Memory

    PubMed Central

    Lorenc, Elizabeth S.; Lee, Taraz G.; Chen, Anthony J.-W.; D’Esposito, Mark

    2015-01-01

    It is proposed that feedback signals from the prefrontal cortex (PFC) to extrastriate cortex are essential for goal-directed processing, maintenance, and selection of information in visual working memory (VWM). In a previous study, we found that disruption of PFC function with transcranial magnetic stimulation (TMS) in healthy individuals impaired behavioral performance on a face/scene matching task and decreased category-specific tuning in extrastriate cortex as measured with functional magnetic resonance imaging (fMRI). In this study, we investigated the effect of disruption of left inferior frontal gyrus (IFG) function on the fidelity of neural representations of two distinct information codes: (1) the stimulus category and (2) the goal-relevance of viewed stimuli. During fMRI scanning, subjects were presented face and scene images in pseudo-random order and instructed to remember either faces or scenes. Within both anatomical and functional regions of interest (ROIs), a multi-voxel pattern classifier was used to quantitatively assess the fidelity of activity patterns representing stimulus category: whether a face or a scene was presented on each trial, and goal relevance, whether the presented image was task relevant (i.e., a face is relevant in a “Remember Faces” block, but irrelevant in a “Remember Scenes” block). We found a reduction in the fidelity of the stimulus category code in visual cortex after left IFG disruption, providing causal evidence that lateral PFC modulates object category codes in visual cortex during VWM. In addition, we found that IFG disruption caused a reduction in the fidelity of the goal relevance code in a distributed set of brain regions. These results suggest that the IFG is involved in determining the task-relevance of visual input and communicating that information to a network of regions involved in further processing during VWM. Finally, we found that participants who exhibited greater fidelity of the goal relevance

  9. [Hospital-acquired urinary tract infections].

    PubMed

    Adukauskiene, Dalia; Cicinskaite, Ilona; Vitkauskiene, Astra; Macas, Andrius; Tamosiūnas, Ramūnas; Kinderyte, Aida

    2006-01-01

    Urinary tract infections are responsible for 40-60% of all hospital-acquired infections. Increased age of patients and comorbid diseases render hospitalized patients more susceptible to infection. Almost 80% of hospital-acquired urinary tract infections are associated with urinary catheters, and only 5-10% of urinary infections are caused by invasive manipulations in the urogenital tract. Pathogens of hospital-acquired urinary tract infections are frequently multi-resistant, and antibiotic therapy can only be successful when the complicating factors are eliminated or urodynamic function is restored. For treatment of complicated hospital-acquired urinary tract infections, the antibiotics must exhibit adequate pharmacodynamic and pharmacokinetic properties: high renal clearance of unmetabolized form with good antimicrobial activity in both acidic and alkaline urine. For selection of empirical treatment of hospital-acquired urinary tract infections, it is necessary to evaluate localization of infection, its severity, possible isolates, and the most frequent pathogens in the department where patient is treated. The best choice for the starting the antimicrobial therapy is the cheapest narrow-spectrum effective antibiotic in the treatment of urinary tract infection until microbiological evaluation of pathogens will be received. Adequate management of urinary tract infections lowers the rate of complications, requirements for antibacterial treatment, selection of multi-resistant isolates and is cost effective.

  10. On the analytical form of the Earth's magnetic attraction expressed as a function of time

    NASA Technical Reports Server (NTRS)

    Carlheim-Gyllenskold, V.

    1983-01-01

    An attempt is made to express the Earth's magnetic attraction in simple analytical form using observations during the 16th to 19th centuries. Observations of the magnetic inclination in the 16th and 17th centuries are discussed.

  11. Chemically functionalized magnetic exchange interactions of hybrid organic-ferromagnetic metal interfaces

    NASA Astrophysics Data System (ADS)

    Friedrich, Rico; Caciuc, Vasile; Kiselev, Nikolai S.; Atodiresei, Nicolae; Blügel, Stefan

    2015-03-01

    We theoretically explore through systematic multiscale ab initio and Monte Carlo calculations how the surface magnetism of a ferromagnetic surface can be fine-tuned by nonmagnetic organic molecules containing a single π bond. We demonstrate that a magnetic hardening or softening can be induced depending on the electronegativity of the heteroatom or when the π -bond "bridges" the magnetic surface atoms. Finally, the Monte Carlo simulations revealed taylored macroscopic hysteresis loops corresponding to soft and hard molecule-surface magnets.

  12. Detection of electron energy distribution function anisotropy in a magnetized electron cyclotron resonance plasma by using a directional Langmuir probe

    SciTech Connect

    Shikama, T. Hasuo, M.; Kitaoka, H.

    2014-07-15

    Anisotropy in the electron energy distribution function (EEDF) in an electron cyclotron resonance plasma with magnetized electrons and weakly magnetized ions is experimentally investigated using a directional Langmuir probe. Under an assumption of independent EEDFs in the directions parallel and perpendicular to the magnetic field, the directional variation of the EEDF is evaluated. In the measured EEDFs, a significantly large population density of electrons with energies larger than 30 eV is found in one of the cross-field directions depending on the magnetic field direction. With the aid of an electron trajectory calculation, it is suggested that the observed anisotropic electrons originate from the EEDF anisotropy and the cross-field electron drift.

  13. Structure, magnetism, and dissociation energy of small bimetallic cobalt-chromium oxide cluster cations: A density-functional-theory study

    NASA Astrophysics Data System (ADS)

    Pham, Hung Tan; Cuong, Ngo Tuan; Tam, Nguyen Minh; Lam, Vu Dinh; Tung, Nguyen Thanh

    2016-01-01

    We study CoxCryOm+ (x + y = 2, 3 and 1 ≤ m ≤ 4) clusters by means of density-functional-theory calculations. It is found that the clusters grow preferentially through maximizing the number of metal-oxygen bonds with a favor on Cr sites. The size- and composition-dependent magnetic behavior is discussed in relation with the local atomic magnetic moments. While doped species show an oscillatory magnetic behavior, the total magnetic moment of pure cobalt and chromium oxide clusters tends to enhance or reduce as increasing the oxygen content, respectively. The dissociation energies for different evaporation channels are also calculated to suggest the stable patterns, as fingerprints for future photofragmentation experiments.

  14. Perfusion MRI Indexes Variability in the Functional Brain Effects of Theta-Burst Transcranial Magnetic Stimulation

    PubMed Central

    Gratton, Caterina; Lee, Taraz G.; Nomura, Emi M.; D’Esposito, Mark

    2014-01-01

    Transcranial Magnetic Stimulation (TMS) is an important tool for testing causal relationships in cognitive neuroscience research. However, the efficacy of TMS can be variable across individuals and difficult to measure. This variability is especially a challenge when TMS is applied to regions without well-characterized behavioral effects, such as in studies using TMS on multi-modal areas in intrinsic networks. Here, we examined whether perfusion fMRI recordings of Cerebral Blood Flow (CBF), a quantitative measure sensitive to slow functional changes, reliably index variability in the effects of stimulation. Twenty-seven participants each completed four combined TMS-fMRI sessions during which both resting state Blood Oxygen Level Dependent (BOLD) and perfusion Arterial Spin Labeling (ASL) scans were recorded. In each session after the first baseline day, continuous theta-burst TMS (TBS) was applied to one of three locations: left dorsolateral prefrontal cortex (L dlPFC), left anterior insula/frontal operculum (L aI/fO), or left primary somatosensory cortex (L S1). The two frontal targets are components of intrinsic networks and L S1 was used as an experimental control. CBF changes were measured both before and after TMS on each day from a series of interleaved resting state and perfusion scans. Although TBS led to weak selective increases under the coil in CBF measurements across the group, individual subjects showed wide variability in their responses. TBS-induced changes in rCBF were related to TBS-induced changes in functional connectivity of the relevant intrinsic networks measured during separate resting-state BOLD scans. This relationship was selective: CBF and functional connectivity of these networks were not related before TBS or after TBS to the experimental control region (S1). Furthermore, subject groups with different directions of CBF change after TBS showed distinct modulations in the functional interactions of targeted networks. These results suggest

  15. Neural Correlates of Emotional Personality: A Structural and Functional Magnetic Resonance Imaging Study

    PubMed Central

    Koelsch, Stefan; Skouras, Stavros; Jentschke, Sebastian

    2013-01-01

    Studies addressing brain correlates of emotional personality have remained sparse, despite the involvement of emotional personality in health and well-being. This study investigates structural and functional brain correlates of psychological and physiological measures related to emotional personality. Psychological measures included neuroticism, extraversion, and agreeableness scores, as assessed using a standard personality questionnaire. As a physiological measure we used a cardiac amplitude signature, the so-called Eκ value (computed from the electrocardiogram) which has previously been related to tender emotionality. Questionnaire scores and Eκ values were related to both functional (eigenvector centrality mapping, ECM) and structural (voxel-based morphometry, VBM) neuroimaging data. Functional magnetic resonance imaging (fMRI) data were obtained from 22 individuals (12 females) while listening to music (joy, fear, or neutral music). ECM results showed that agreeableness scores correlated with centrality values in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the ventral striatum (nucleus accumbens). Individuals with higher Eκ values (indexing higher tender emotionality) showed higher centrality values in the subiculum of the right hippocampal formation. Structural MRI data from an independent sample of 59 individuals (34 females) showed that neuroticism scores correlated with volume of the left amygdaloid complex. In addition, individuals with higher Eκ showed larger gray matter volume in the same portion of the subiculum in which individuals with higher Eκ showed higher centrality values. Our results highlight a role of the amygdala in neuroticism. Moreover, they indicate that a cardiac signature related to emotionality (Eκ) correlates with both function (increased network centrality) and structure (grey matter volume) of the subiculum of the hippocampal formation, suggesting a role of the hippocampal formation for emotional

  16. Carbodiimide-mediated immobilization of serratiopeptidase on amino-, carboxyl-functionalized magnetic nanoparticles and characterization for target delivery

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep; Jana, Asim K.; Maiti, Mithu; Dhamija, Isha

    2014-02-01

    A hybrid biomaterial of serratiopeptidase enzyme was prepared with magnetic nanoparticles (MNPs) via carboxyl and amino-functionalization and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) for direct immobilization. The average size of prepared MNPs was found to be 15.05 ± 3.06 nm. Attachment of amino and carboxyl groups was confirmed by Fourier transform infrared spectroscopy. X-ray diffraction confirmed the purity and phase integrity of Fe3O4. The MNPs and enzyme-loaded-MNPs (EMNPs) were of saturation magnetization 58 and 50 emu g-1, respectively. Thermogravimetric analysis of EDC-MNPs and EMNPs showed the presence of organic coating over MNPs. Serratiopeptidase immobilized on amino-functionalized magnetic nanoparticles showed loss of enzyme activity due to crosslinking of enzyme, while serratiopeptidase immobilized on carboxyl-functionalized magnetic nanoparticles was better and gave 115.78 mg protein g-1 MNPs, enzyme loading 168.32 U g-1 MNPs at optimized MNPs-to-enzyme ratio 1.0 mg mg-1. In vitro and in vivo studies showed that EMNPs with magnetic targeting is more effective in drug permeation and reduction in edema than free enzyme.

  17. Pharmacokinetic/pharmacodynamic analysis to evaluate ceftaroline fosamil dosing regimens for the treatment of community-acquired bacterial pneumonia and complicated skin and skin-structure infections in patients with normal and impaired renal function.

    PubMed

    Canut, A; Isla, A; Rodríguez-Gascón, A

    2015-04-01

    In this study, the probability of pharmacokinetic/pharmacodynamic target attainment (PTA) of ceftaroline against clinical isolates causing community-acquired bacterial pneumonia (CABP) and complicated skin and skin-structure infection (cSSSI) in Europe was evaluated. Three dosing regimens were assessed: 600 mg every 12 h (q12 h) as a 1-h infusion (standard dose) or 600 mg every 8 h (q8 h) as a 2-h infusion in virtual patients with normal renal function; and 400 mg q12 h as a 1-h infusion in patients with moderate renal impairment. Pharmacokinetic and microbiological data were obtained from the literature. The PTA and the cumulative fraction of response (CFR) were calculated by Monte Carlo simulation. In patients with normal renal function, the ceftaroline standard dose (600 mg q12 h as a 1-h infusion) can be sufficient to treat CABP due to ceftazidime-susceptible (CAZ-S) Escherichia coli, CAZ-S Klebsiella pneumoniae, meticillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis (CFR>90%). However, against meticillin-resistant S. aureus (MRSA), the CFR was 72%. In cSSSI, the CFR was also <80% for MRSA. Administration of ceftaroline 600 mg q8 h as a 2-h infusion or 400 mg q12 h as a 1-h infusion in patients with moderate renal insufficiency provided a high probability of treatment success (CFR ca. 100%) for most micro-organisms causing CABP and cSSSI, including MRSA and penicillin-non-susceptible S. pneumoniae. These results suggest that in patients with normal renal function, ceftaroline 600 mg q8 h as a 2-h infusion may be a better option than the standard dose, especially if the MRSA rate is high.

  18. Physiological recordings: Basic concepts and implementation during functional magnetic resonance imaging

    PubMed Central

    Gray, Marcus A.; Minati, Ludovico; Harrison, Neil A.; Gianaros, Peter J.; Napadow, Vitaly; Critchley, Hugo D.

    2009-01-01

    Combining human functional neuroimaging with other forms of psychophysiological measurement, including autonomic monitoring, provides an empirical basis for understanding brain–body interactions. This approach can be applied to characterize unwanted physiological noise, examine the neural control and representation of bodily processes relevant to health and morbidity, and index covert expression of affective and cognitive processes to enhance the interpretation of task-evoked regional brain activity. In recent years, human neuroimaging has been dominated by functional magnetic resonance imaging (fMRI) studies. The spatiotemporal information of fMRI regarding central neural activity is valuably complemented by parallel physiological monitoring, yet such studies still remain in the minority. This review article highlights fMRI studies that employed cardiac, vascular, respiratory, electrodermal, gastrointestinal and pupillary psychophysiological indices to address specific questions regarding interaction between brain and bodily state in the context of experience, cognition, emotion and behaviour. Physiological monitoring within the fMRI environment presents specific technical issues, most importantly related to safety. Mechanical and electrical hazards may present dangers to scanned subjects, operator and/or equipment. Furthermore, physiological monitoring may interfere with the quality of neuroimaging data, or itself be compromised by artefacts induced by the operation of the scanner. We review the sources of these potential problems and the current approaches and advice to enable the combination of fMRI and physiological monitoring in a safe and effective manner. PMID:19460445

  19. Density functional calculations for structural, electronic, and magnetic properties of gadolinium-oxide clusters

    SciTech Connect

    Yuan, H. K.; Chen, H. Tian, C. L.; Kuang, A. L.; Wang, J. Z.

    2014-04-21

    Gadolinium-oxide clusters in various sizes and stoichiometries have been systematically studied by employing the density functional theory with the generalized gradient approximation. The clusters in bulk stoichiometry are relatively more stable and their binding energies increase with the increasing size. Stoichiometric (Gd{sub 2}O{sub 3}){sub n} clusters of n = 1–3 prefer cage-like structures, whereas the clusters of n = 4–30 prefer compact structures layered by wedge-like units and exhibit a rough feature toward the bulk-like arrangement with small disorders of atomic positions. The polyhedral-cages analogous to carbon-fullerenes are stable isomers yet not the minimum energy configurations. Their stabilities can be improved by embedding one oxygen atom or a suitable cage to form core-shell configurations. The mostly favored antiferromagnetic couplings between adjacent Gd atoms are nearly degenerated in energy with their ferromagnetic couplings, resulting in super-paramagnetic characters of gadolinium-oxide clusters. The Ruderman-Kittel-Kasuya-Yosida (RKKY)-type mechanism together with the superexchange-type mechanism plays cooperation role for the magnetic interactions in clusters. We present, as a function of n, calculated binding energies, ionization potential, electron affinity, and electronic dipole moment.

  20. 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

  1. A method to analyze low signal-to-noise ratio functional magnetic resonance imaging data.

    PubMed

    Zhu, Xi; Kayali, M Amin; Jansen, Ben H

    2015-09-01

    The current practice of using a single, representative hemodynamic response function (canonical HRF) to model functional magnetic resonance imaging (fMRI) data is questionable given the trial-to-trial variability of the brain's responses. In addition, the changes in blood-oxygenation level due to sensory stimulation may be small, especially when auditory stimuli are used. Here we introduce a correlation-based single trial analysis method for fMRI data analysis to deal with the low signal-to-noise (SNR) ratio and variability of the HRF in response to repeated, identical auditory stimuli. The correlation technique identifies the "active" trials, i.e., those showing a robust hemodynamic response among all single trials. Using data collected from 14 healthy subjects, it was found that the correlation method can find significant differences between brain areas and brain states in actual fMRI data. Also, the correlation-based method confirmed that the superior temporal gyrus (STG), inferior frontal gyrus (IFG), dorsolateral prefrontal cortex (DLPFC) and thalamus (THA) are involved in auditory information processing in general, and the involvement of the bilateral STG, right THA and left DLPFC in sensory gating. In contrast, conventional analysis failed to find any regions involved in sensory gating. The findings suggest that our single trial analysis method can increase the sensitivity of fMRI data analysis.

  2. Suggestion-Induced Modulation of Semantic Priming during Functional Magnetic Resonance Imaging

    PubMed Central

    Ulrich, Martin; Kiefer, Markus; Bongartz, Walter; Grön, Georg; Hoenig, Klaus

    2015-01-01

    Using functional magnetic resonance imaging during a primed visual lexical decision task, we investigated the neural and functional mechanisms underlying modulations of semantic word processing through hypnotic suggestions aimed at altering lexical processing of primes. The priming task was to discriminate between target words and pseudowords presented 200 ms after the prime word which was semantically related or unrelated to the target. In a counterbalanced study design, each participant performed the task once at normal wakefulness and once after the administration of hypnotic suggestions to perceive the prime as a meaningless symbol of a foreign language. Neural correlates of priming were defined as significantly lower activations upon semantically related compared to unrelated trials. We found significant suggestive treatment-induced reductions in neural priming, albeit irrespective of the degree of suggestibility. Neural priming was attenuated upon suggestive treatment compared with normal wakefulness in brain regions supporting automatic (fusiform gyrus) and controlled semantic processing (superior and middle temporal gyri, pre- and postcentral gyri, and supplementary motor area). Hence, suggestions reduced semantic word processing by conjointly dampening both automatic and strategic semantic processes. PMID:25923740

  3. A Polymeric Fastener can Easily Functionalize Liposome Surfaces with Gadolinium for Enhanced Magnetic Resonance Imaging

    PubMed Central

    Smith, Cartney E.; Shkumatov, Artem; Withers, Sarah G.; Glockner, James F.; Misra, Sanjay; Roy, Edward J.; Wong, Chun-Ho; Zimmerman, Steven C.; Kong, Hyunjoon

    2013-01-01

    Common methods of loading magnetic resonance imaging (MRI) contrast agents into nanoparticles often suffer from challenges related to particle formation, complex chemical modification/purification steps, and reduced contrast efficiency. This study presents a simple, yet advanced process to address these issues by loading gadolinium, an MRI contrast agent, exclusively on a liposome surface using a polymeric fastener. The fastener, so named for its ability to physically link the two functional components together, consisted of chitosan substituted with diethylenetriaminepentaacetic acid (DTPA) to chelate gadolinium, as well as octadecyl chains to stabilize the modified chitosan on the liposome surface. The assembly strategy, mimicking the mechanisms by which viruses and proteins naturally anchor to a cell, provided greater T1 relaxivity than liposomes loaded with gadolinium in both the interior and outer leaflet. Gadolinium-coated liposomes were ultimately evaluated in vivo using murine ischemia models to highlight the diagnostic capability of the system. Taken together, this process decouples particle assembly and functionalization, and therefore has considerable potential to enhance imaging quality while alleviating many of the difficulties associated with multifunctional particle fabrication. PMID:24083377

  4. Horizontal Long Axis Imaging Plane for Evaluation of Right Ventricular Function on Cardiac Magnetic Resonance Imaging

    PubMed Central

    Chaturvedi, Abhishek; Whitnah, Joseph; Maki, Jeffrey H; Baran, Timothy; Mitsumori, Lee M

    2016-01-01

    Purpose: The purpose of this study was to evaluate a horizontal long axis (HLA) magnetic resonance imaging (MRI) plane aligned to the long axis of the right ventricular (RV) cavity for functional analysis by comparing the measurement variability and time required for the analysis with that using a short-axis (SAX) image orientation. Materials and Methods: Thirty-four cardiac MRI exams with cine balanced steady-state free precession image stacks in both the SAX and the HLA of the RV (RHLA) were evaluated. Two reviewers independently traced RV endocardial borders on each image of the cine stacks. The time required to complete each set of traces was recorded, and the RV end-diastolic volume, end-systolic volume, and ejection fraction were calculated. Analysis times and RV measurements were compared between the two orientations. Results: Analysis time for each reviewer was significantly shorter for the RHLA stack (reviewer 1 = 6.4 ± 1.8 min, reviewer 2 = 6.0 ± 3.3 min) than for the SAX stack (7.5 ± 2.1 and 6.9 ± 3.6 min, respectively; P < 0.002). Bland–Altman analysis revealed lower mean differences, limits of agreement, and coefficients of variation for RV measurements obtained with the RHLA stack. Conclusions: RV functional analysis using a RHLA stack resulted in shorter analysis times and lower measurement variability than for a SAX stack orientation. PMID:28123842

  5. Cognitive Modules Utilized for Narrative Comprehension in Children: A Functional Magnetic Resonance Imaging Study

    PubMed Central

    Schmithorst, Vincent J.; Holland, Scott K.; Plante, Elena

    2005-01-01

    The ability to comprehend narratives constitutes an important component of human development and experience. The neural correlates of auditory narrative comprehension in children were investigated in a large-scale functional magnetic resonance imaging (fMRI) study involving 313 subjects ages 5–18. Using group Independent Component Analysis (ICA), bilateral task-related components were found comprising the primary auditory cortex, the mid-superior temporal gyrus, the hippocampus, the angular gyrus and medial aspect of the parietal lobule (precuneus/posterior cingulate). In addition, a right-lateralized component was found involving the most posterior aspect of the superior temporal gyrus, and a left-lateralized component was found comprising the inferior frontal gyrus (including Broca’s area), the inferior parietal lobule, and the medial temporal gyrus. Using a novel data-driven analysis technique, increased task-related activity related to age was found in the components comprising the mid-superior temporal gyrus (Wernicke’s area) and the posterior aspect of the superior temporal gyrus, while decreased activity related to age was found in the component comprising the angular gyrus. The results are discussed in light of recent hypotheses involving the functional segregation of Wernicke’s area and the specific role of the mid-superior temporal gyrus in speech comprehension. PMID:16109491

  6. Physiological recordings: basic concepts and implementation during functional magnetic resonance imaging.

    PubMed

    Gray, Marcus A; Minati, Ludovico; Harrison, Neil A; Gianaros, Peter J; Napadow, Vitaly; Critchley, Hugo D

    2009-09-01

    Combining human functional neuroimaging with other forms of psychophysiological measurement, including autonomic monitoring, provides an empirical basis for understanding brain-body interactions. This approach can be applied to characterize unwanted physiological noise, examine the neural control and representation of bodily processes relevant to health and morbidity, and index covert expression of affective and cognitive processes to enhance the interpretation of task-evoked regional brain activity. In recent years, human neuroimaging has been dominated by functional magnetic resonance imaging (fMRI) studies. The spatiotemporal information of fMRI regarding central neural activity is valuably complemented by parallel physiological monitoring, yet such studies still remain in the minority. This review article highlights fMRI studies that employed cardiac, vascular, respiratory, electrodermal, gastrointestinal and pupillary psychophysiological indices to address specific questions regarding interaction between brain and bodily state in the context of experience, cognition, emotion and behaviour. Physiological monitoring within the fMRI environment presents specific technical issues, most importantly related to safety. Mechanical and electrical hazards may present dangers to scanned subjects, operator and/or equipment. Furthermore, physiological monitoring may interfere with the quality of neuroimaging data, or itself be compromised by artefacts induced by the operation of the scanner. We review the sources of these potential problems and the current approaches and advice to enable the combination of fMRI and physiological monitoring in a safe and effective manner.

  7. Comparing diffuse optical tomography and functional magnetic resonance imaging signals during a cognitive task: pilot study.

    PubMed

    Hernández-Martin, Estefania; Marcano, Francisco; Casanova, Oscar; Modroño, Cristian; Plata-Bello, Julio; González-Mora, Jose Luis

    2017-01-01

    Diffuse optical tomography (DOT) measures concentration changes in both oxy- and deoxyhemoglobin providing three-dimensional images of local brain activations. A pilot study, which compares both DOT and functional magnetic resonance imaging (fMRI) volumes through t-maps given by canonical statistical parametric mapping (SPM) processing for both data modalities, is presented. The DOT series were processed using a method that is based on a Bayesian filter application on raw DOT data to remove physiological changes and minimum description length application index to select a number of singular values, which reduce the data dimensionality during image reconstruction and adaptation of DOT volume series to normalized standard space. Therefore, statistical analysis is performed with canonical SPM software in the same way as fMRI analysis is done, accepting DOT volumes as if they were fMRI volumes. The results show the reproducibility and ruggedness of the method to process DOT series on group analysis using cognitive paradigms on the prefrontal cortex. Difficulties such as the fact that scalp-brain distances vary between subjects or cerebral activations are difficult to reproduce due to strategies used by the subjects to solve arithmetic problems are considered. T-images given by fMRI and DOT volume series analyzed in SPM show that at the functional level, both DOT and fMRI measures detect the same areas, although DOT provides complementary information to fMRI signals about cerebral activity.

  8. [Functional magnetic resonance imaging in the determination of dominant language cerebral area].

    PubMed

    Meneses, Murilo S; Rocha, Samanta F Blattes; Blood, Marcelo R Young; Trentin, Alcides; Benites Filho, Paulo Roberto; Kowacs, Pedro André; Oliveira, Nelson de Andrade; Simão, Cristiane A; Awamura, Yumi; Vítola, Maria L A

    2004-03-01

    Functional magnetic resonance imaging (fMRI) is a technique for detecting minimal changes in brain perfusion and oxygenation secondary to neuronal activation. Its application in the pre-surgical evaluation of epileptic patients with temporal mesial sclerosis is currently being under investigation in several centers. This study aims to describe an activation paradigm for the evaluation of language and memory functions, as an alternative to the worldwide used Wada test, which is an invasive procedure. In order to propose a paradigm adapted to the Portuguese language, we report our experience in determining the dominant cerebral area for language through fMRI with a verbal fluency task. The results of the fMRI from 19 patients studied in Curitiba in a period of approximately two years were studied. Sixteen of them presented with left hemispheric cerebral language dominance. In five patients, results from fMRI and Wada test could be compared and agreed in localization. Our results reinforce the view that fMRI may become an essential tool for medical practice, perhaps for the determination of eloquent areas in the evaluation of candidates for epilepsy surgery.

  9. Retrospective coregistration of functional magnetic resonance imaging data using external monitoring.

    PubMed

    Tremblay, Marleine; Tam, Fred; Graham, Simon J

    2005-01-01

    Coregistration is essential for correcting head motion artifacts in functional magnetic resonance imaging (fMRI). Coregistration algorithms typically realign images through optimization of a similarity measure based on voxel signal intensities. However, coregistration can also be performed through external monitoring, whereby a tracking device measures head motion directly and independently of the imaging data. This paper describes development of external monitoring using fMRI-compatible infrared cameras. Three subjects participated in block-design fMRI experiments consisting of bilateral finger tapping alone and tapping combined with visuomotor tracking to produce controlled task-correlated head motion. Functional MRI time-series were coregistered using the external monitoring technique and a known image-based algorithm for comparison. Over various performance characteristics, external monitoring and image-based coregistration exhibited good agreement, in particular reducing signals correlated with millimeter task-correlated motions by 50-100%, with a 5% difference between the two techniques. These results promise future applications and refinements of external monitoring in patient populations where head motion is especially problematic. Possibilities include 3D prospective coregistration during real-time fMRI, coregistration of individual slices, and motion correction in anatomic MRI.

  10. Surface-based analysis methods for high-resolution functional magnetic resonance imaging

    PubMed Central

    Khan, Rez; Zhang, Qin; Darayan, Shayan; Dhandapani, Sankari; Katyal, Sucharit; Greene, Clint; Bajaj, Chandra; Ress, David

    2011-01-01

    Functional magnetic resonance imaging (fMRI) has become a popular technique for studies of human brain activity. Typically, fMRI is performed with >3-mm sampling, so that the imaging data can be regarded as two-dimensional samples that average through the 1.5—4-mm thickness of cerebral cortex. The increasing use of higher spatial resolutions, <1.5-mm sampling, complicates the analysis of fMRI, as one must now consider activity variations within the depth of the brain tissue. We present a set of surface-based methods to exploit the use of high-resolution fMRI for depth analysis. These methods utilize white-matter segmentations coupled with deformable-surface algorithms to create a smooth surface representation at the gray-white interface and pial membrane. These surfaces provide vertex positions and normals for depth calculations, enabling averaging schemes that can increase contrast-to-noise ratio, as well as permitting the direct analysis of depth profiles of functional activity in the human brain. PMID:22125419

  11. Associative Learning Through Acquired Salience

    PubMed Central

    Treviño, Mario

    2016-01-01

    Most associative learning studies describe the salience of stimuli as a fixed learning-rate parameter. Presumptive saliency signals, however, have also been linked to motivational and attentional processes. An interesting possibility, therefore, is that discriminative stimuli could also acquire salience as they become powerful predictors of outcomes. To explore this idea, we first characterized and extracted the learning curves from mice trained with discriminative images offering varying degrees of structural similarity. Next, we fitted a linear model of associative learning coupled to a series of mathematical representations for stimulus salience. We found that the best prediction, from the set of tested models, was one in which the visual salience depended on stimulus similarity and a non-linear function of the associative strength. Therefore, these analytic results support the idea that the net salience of a stimulus depends both on the items' effective salience and the motivational state of the subject that learns about it. Moreover, this dual salience model can explain why learning about a stimulus not only depends on the effective salience during acquisition but also on the specific learning trajectory that was used to reach this state. Our mathematical description could be instrumental for understanding aberrant salience acquisition under stressful situations and in neuropsychiatric disorders like schizophrenia, obsessive-compulsive disorder, and addiction. PMID:26793078

  12. In Vivo NMR Studies of the Brain with Hereditary or Acquired Metabolic Disorders.

    PubMed

    Sherry, Erica B; Lee, Phil; Choi, In-Young

    2015-12-01

    Metabolic disorders, whether hereditary or acquired, affect the brain, and abnormalities of the brain are related to cellular integrity; particularly in regard to neurons and astrocytes as well as interactions between them. Metabolic disturbances lead to alterations in cellular function as well as microscopic and macroscopic structural changes in the brain with diabetes, the most typical example of metabolic disorders, and a number of hereditary metabolic disorders. Alternatively, cellular dysfunction and degeneration of the brain lead to metabolic disturbances in hereditary neurological disorders with neurodegeneration. Nuclear magnetic resonance (NMR) techniques allow us to assess a range of pathophysiological changes of the brain in vivo. For example, magnetic resonance spectroscopy detects alterations in brain metabolism and energetics. Physiological magnetic resonance imaging (MRI) detects accompanying changes in cerebral blood flow related to neurovascular coupling. Diffusion and T1/T2-weighted MRI detect microscopic and macroscopic changes of the brain structure. This review summarizes current NMR findings of functional, physiological and biochemical alterations within a number of hereditary and acquired metabolic disorders in both animal models and humans. The global view of the impact of these metabolic disorders on the brain may be useful in identifying the unique and/or general patterns of abnormalities in the living brain related to the pathophysiology of the diseases, and identifying future fields of inquiry.

  13. Structural and Functional Magnetic Resonance Imaging of the Cerebellum: Considerations for Assessing Cerebellar Ataxias.

    PubMed

    Deistung, Andreas; Stefanescu, Maria R; Ernst, Thomas M; Schlamann, Marc; Ladd, Mark E; Reichenbach, Jürgen R; Timmann, Dagmar

    2016-02-01

    Magnetic resonance imaging (MRI) of the brain is of high interest for diagnosing and understanding degenerative ataxias. Here, we present state-of-the-art MRI methods to characterize structural alterations of the cerebellum and introduce initial experiments to show abnormalities in the cerebellar nuclei. Clinically, T1-weighted MR images are used to assess atrophy of the cerebellar cortex, the brainstem, and the spinal cord, whereas T2-weighted and PD-weighted images are typically employed to depict potential white matter lesions that may be associated with certain types of ataxias. More recently, attention has also focused on the characterization of the cerebellar nuclei, which are discernible on spatially highly resolved iron-sensitive MR images due to their relatively high iron content, including T2 (*)-weighted images, susceptibility-weighted images (SWI), effective transverse relaxation rate (R2 (*)) maps, and quantitative susceptibility maps (QSM). Among these iron-sensitive techniques, QSM reveals the best contrast between cerebellar nuclei and their surroundings. In particular, the gyrification of the dentate nuclei is prominently depicted, even at the clinically widely available field strength of 3 T. The linear relationship between magnetic susceptibility and local iron content allows for determination of iron deposition in cerebellar nuclei non-invasively. The increased signal-to-noise ratio of ultrahigh-field MRI (B0 ≥ 7 T) and advances in spatial normalization methods enable functional MRI (fMRI) at the level of the cerebellar cortex and cerebellar nuclei. Data from initial fMRI studies are presented in three common forms of hereditary ataxias (Friedreich's ataxia, spinocerebellar ataxia type 3, and spinocerebellar ataxia type 6). Characteristic changes in the fMRI signal are discussed in the light of histopathological data and current knowledge of the underlying physiology of the fMRI signal in the cerebellum.

  14. On the significance of the area under the after-effect function curve of a magnetic fluid.

    PubMed

    Fannin, P C; Marin, C N; Couper, C

    2008-05-21

    The after-effect function, b(t), describes how the magnetization of a dissipative magnetic fluid decreases with time when a polarizing field, H, is suddenly removed. It is shown that with increasing H, the rate of decay of b(t) increases and also that the area, [Formula: see text], under each decay curve decreases. Here we investigate the significance of this and by means of a simple model, show that the normalized function, B/b(0), is in fact equal to the Debye relaxation time τ(D). The results of applying the model to theoretically generated data and also to data obtained from a magnetic fluid sample are presented.

  15. Critical Analysis of Cluster Models and Exchange-Correlation Functionals for Calculating Magnetic Shielding in Molecular Solids.

    PubMed

    Holmes, Sean T; Iuliucci, Robbie J; Mueller, Karl T; Dybowski, Cecil

    2015-11-10

    Calculations of the principal components of magnetic-shielding tensors in crystalline solids require the inclusion of the effects of lattice structure on the local electronic environment to obtain significant agreement with experimental NMR measurements. We assess periodic (GIPAW) and GIAO/symmetry-adapted cluster (SAC) models for computing magnetic-shielding tensors by calculations on a test set containing 72 insulating molecular solids, with a total of 393 principal components of chemical-shift tensors from 13C, 15N, 19F, and 31P sites. When clusters are carefully designed to represent the local solid-state environment and when periodic calculations include sufficient variability, both methods predict magnetic-shielding tensors that agree well with experimental chemical-shift values, demonstrating the correspondence of the two computational techniques. At the basis-set limit, we find that the small differences in the computed values have no statistical significance for three of the four nuclides considered. Subsequently, we explore the effects of additional DFT methods available only with the GIAO/cluster approach, particularly the use of hybrid-GGA functionals, meta-GGA functionals, and hybrid meta-GGA functionals that demonstrate improved agreement in calculations on symmetry-adapted clusters. We demonstrate that meta-GGA functionals improve computed NMR parameters over those obtained by GGA functionals in all cases, and that hybrid functionals improve computed results over the respective pure DFT functional for all nuclides except 15N.

  16. The contribution of common surgically implanted hardware to functional magnetic resonance imaging artifacts

    PubMed Central

    Desai, Aditi A.; Strother, Megan K.; Faraco, Carlos C.; Morgan, Victoria L.; Ladner, Travis R.; Dethrage, Lindsey M.; Jordan, Lori C.; Donahue, Manus J.

    2015-01-01

    Background and Purpose Blood-oxygenation-level-dependent (BOLD) MRI is increasingly utilized clinically to assess cerebrovascular reactivity (CVR) and/or language and motor function. However, many patients have metallic implants which induce susceptibility artifacts, rendering the functional information uninformative. Here, we calculate and interpret BOLD MRI artifact impact arising from surgically implanted hardware. Material and Methods An analysis of BOLD MRIs (n=343; B0=3.0T; TE=35 ms; gradient-echo EPI) acquired clinically (year range=2006–2014) at our hospital was performed. BOLD MRIs were commonly prescribed for patients with cerebrovascular disease (n=80) or patients undergoing language or motor localization (n=263). Artifact volume (cm3) and its impact on clinical interpretation were determined by a board-certified neuroradiologist. Results Mean artifact volume associated with intracranial hardware was 4.3±3.2 cm3 (range=1.1–9.4 cm3). Mean artifact volume from extracranial hardware in cerebrovascular disease patients was 28.4 ±14.0 cm3 (range=6.1–61.7 cm3), and in other patients was 39.9±27.0 cm3 (range=6.9–77.1 cm3). Mean artifact volume of ventriculoperitoneal shunts was 95.7±39.3 cm3 (range=64.0–139.6 cm3). Artifact had no-to-mild effect on clinical interpretability of all patients with intracranial implants. Extracranial hardware artifact had no-to-moderate impact on clinical interpretability, with the exception of one patient with 12 KLS Martin maxDrive screws with severe artifact precluding clinical interpretation. All examined ventriculoperitoneal shunts resulted in moderate-to-severe artifacts, limiting clinical interpretation. Conclusions BOLD MRI yields interpretable functional maps in most patients beyond a small (30–40 cm3) artifact surrounding the hardware. Exceptions were ventriculoperitoneal shunts, particularly those with programmable valves and siphon gauges, and large numbers of KLS Martin maxDrive screws. PMID:26272973

  17. Fundamentals and applications of magnetic particle imaging.

    PubMed

    Borgert, Jörn; Schmidt, Joachim D; Schmale, Ingo; Rahmer, Jürgen; Bontus, Claas; Gleich, Bernhard; David, Bernd; Eckart, Rainer; Woywode, Oliver; Weizenecker, Jürgen; Schnorr, Jörg; Taupitz, Matthias; Haegele, Julian; Vogt, Florian M; Barkhausen, Jörg

    2012-01-01

    Magnetic particle imaging (MPI) is a new medical imaging technique which performs a direct measurement of magnetic nanoparticles, also known as superparamagnetic iron oxide. MPI can acquire quantitative images of the local distribution of the magnetic material with high spatial and temporal resolution. Its sensitivity is well above that of other methods used for the detection and quantification of magnetic materials, for example, magnetic resonance imaging. On the basis of an intravenous injection of magnetic particles, MPI has the potential to play an important role in medical application areas such as cardiovascular, oncology, and also in exploratory fields such as cell labeling and tracking. Here, we present an introduction to the basic function principle of MPI, together with an estimation of the spatial resolution and the detection limit. Furthermore, the above-mentioned medical applications are discussed with respect to an applicability of MPI.

  18. Vision Therapy in Adults with Convergence Insufficiency: Clinical and Functional Magnetic Resonance Imaging Measures

    PubMed Central

    Alvarez, Tara L.; Vicci, Vincent R.; Alkan, Yelda; Kim, Eun H.; Gohel, Suril; Barrett, Anna M.; Chiaravalloti, Nancy; Biswal, Bharat B.

    2011-01-01

    Purpose This research quantified clinical measurements and functional neural changes associated with vision therapy in subjects with convergence insufficiency (CI). Methods Convergence and divergence 4° step responses were compared between 13 control adult subjects with normal binocular vision and four CI adult subjects. All CI subjects participated in 18 h of vision therapy. Clinical parameters quantified throughout the therapy included: nearpoint of convergence, recovery point of convergence, positive fusional vergence at near, near dissociated phoria, and eye movements that were quantified using peak velocity. Neural correlates of the CI subjects were quantified with functional magnetic resonance imaging scans comparing random vs. predictable vergence movements using a block design before and after vision therapy. Images were quantified by measuring the spatial extent of activation and the average correlation within five regions of interests (ROI). The ROIs were the dorsolateral prefrontal cortex, a portion of the frontal lobe, part of the parietal lobe, the cerebellum, and the brain stem. All measurements were repeated 4 months to 1 year post-therapy in three of the CI subjects. Results Convergence average peak velocities to step stimuli were significantly slower (p = 0.016) in CI subjects compared with controls; however, significant differences in average peak velocities were not observed for divergence step responses (p = 0.30). The investigation of CI subjects participating in vision therapy showed that the nearpoint of convergence, recovery point of convergence, and near dissociated phoria significantly decreased. Furthermore, the positive fusional vergence, average peak velocity from 4° convergence steps, and the amount of functional activity within the frontal areas, cerebellum, and brain stem significantly increased. Several clinical and cortical parameters were significantly correlated. Conclusions Convergence peak velocity was significantly slower in

  19. A Preliminary Transcranial Magnetic Stimulation Study of Cortical Inhibition and Excitability in High-Functioning Autism and Asperger Disorder

    ERIC Educational Resources Information Center

    Enticott, Peter G.; Rinehart, Nicole J.; Tonge, Bruce J.; Bradshaw, John L.; Fitzgerald, Paul B.

    2010-01-01

    Aim: Controversy surrounds the distinction between high-functioning autism (HFA) and Asperger disorder, but motor abnormalities are associated features of both conditions. This study examined motor corti