Numerical investigation of electron localization in polymer chains

NASA Astrophysics Data System (ADS)

Paulsson, Magnus; Stafström, Sven

1998-01-01

Using finite-size scaling, we have calculated the localization-delocalization phase diagrams for electronic wave functions in different disordered polymeric systems. The disorder considered here simulates finite polymer chain lengths, breaks in the conjugation, and disorder in an external potential. It is shown that a system of interacting chains, even at rather weak interchain interactions, allows for enough flexibility for the scattered waves to avoid dephasing and localization. Localization and the metal-insulator transition in highly conducting polymers are discussed in view of these results.

Weak- versus strong-disorder superfluid—Bose glass transition in one dimension

NASA Astrophysics Data System (ADS)

Doggen, Elmer V. H.; Lemarié, Gabriel; Capponi, Sylvain; Laflorencie, Nicolas

2017-11-01

Using large-scale simulations based on matrix product state and quantum Monte Carlo techniques, we study the superfluid to Bose glass transition for one-dimensional attractive hard-core bosons at zero temperature, across the full regime from weak to strong disorder. As a function of interaction and disorder strength, we identify a Berezinskii-Kosterlitz-Thouless critical line with two different regimes. At small attraction where critical disorder is weak compared to the bandwidth, the critical Luttinger parameter Kc takes its universal Giamarchi-Schulz value Kc=3 /2 . Conversely, a nonuniversal Kc>3 /2 emerges for stronger attraction where weak-link physics is relevant. In this strong-disorder regime, the transition is characterized by self-similar power-law-distributed weak links with a continuously varying characteristic exponent α .

Eculizumab Injection

MedlinePlus

... myasthenia gravis (MG; a disorder of the nervous system that causes muscle weakness). Eculizumab injection is in a group of medications called monoclonal antibodies. It works by blocking the activity of the part of the immune system that may damage blood cells in people with ...

Direct weak localization signature with ultracold atoms: the CBS revival

NASA Astrophysics Data System (ADS)

Josse, Vincent

2016-05-01

Ultracold atomic systems in presence of disorder have attracted a lot of interest over the past decade, in particular to study the physics of Anderson localization (AL) in a renewed perspective. Landmark experiments have been demonstrated, in 1D and 3D geometries. However many challenges remain and new ideas have emerged, as for instance the search for original signatures of Anderson localization in momentum space. Here I will describe our progresses along that line where a weak localization effect has been directly observed, i.e. the Coherent Backscattering (CBS) phenomenon. In particular I will report on the recent observation of suppression and revival of CBS when a controlled dephasing kick is applied to the system. This observation demonstrates a novel and general method, introduced by T. Micklitz and coworkers, to study probe phase coherence in disordered systems by manipulating time reversal symmetry.

Localization and delocalization of a one-dimensional system coupled with the environment

NASA Astrophysics Data System (ADS)

Zhu, Hong-Jun; Xiong, Shi-Jie

2010-03-01

We investigate several models of a one-dimensional chain coupling with surrounding atoms to elucidate disorder-induced delocalization in quantum wires, a peculiar behaviour against common wisdom. We show that the localization length is enhanced by disorder of side sites in the case of strong disorder, but in the case of weak disorder there is a plateau in this dependence. The above behaviour is the conjunct influence of the coupling to the surrounding atoms and the antiresonant effect. We also discuss different effects and their physical origin of different types of disorder in such systems. The numerical results show that coupling with the surrounding atoms can induce either the localization or delocalization effect depending on the values of parameters.

Chickenpox

MedlinePlus

... Better? When Should I Call the Doctor? Print What Is Chickenpox? Chickenpox is a viral infection that causes ... weak immune systems or skin disorders like eczema . What Causes Chickenpox? Chickenpox is caused by the varicella-zoster virus (VZV). This ...

Common Childhood Orthopedic Conditions

MedlinePlus

... might be linked to other conditions, such as cerebral palsy, muscle weakness disorders, autism, or other nervous system ... be related to existing medical problems such as cerebral palsy. Doctors rarely have to treat pigeon-toed feet. ...

Metallic phases from disordered (2+1)-dimensional quantum electrodynamics

DOE PAGES

Goswami, Pallab; Goldman, Hart; Raghu, S.

2017-06-15

Metallic phases have been observed in several disordered two-dimensional (2D) systems, including thin films near superconductor-insulator transitions and quantum Hall systems near plateau transitions. The existence of 2D metallic phases at zero temperature generally requires an interplay of disorder and interaction effects. Consequently, experimental observations of 2D metallic behavior have largely defied explanation. We formulate a general stability criterion for strongly interacting, massless Dirac fermions against disorder, which describe metallic ground states with vanishing density of states. We show that (2+1)-dimensional quantum electrodynamics (QED 3) with a large, even number of fermion flavors remains metallic in the presence of weakmore » scalar potential disorder due to the dynamic screening of disorder by gauge fluctuations. In conclusion, we also show that QED 3 with weak mass disorder exhibits a stable, dirty metallic phase in which both interactions and disorder play important roles.« less

Coulomb disorder in three-dimensional Dirac materials

NASA Astrophysics Data System (ADS)

Skinner, Brian

2015-03-01

In three-dimensional materials with a Dirac spectrum, weak short-ranged disorder is essentially irrelevant near the Dirac point. This is manifestly not the case for Coulomb disorder, where the long-ranged nature of the potential produced by charged impurities implies large fluctuations of the disorder potential even when impurities are sparse, and these fluctuations are screened by the formation of electron/hole puddles. Here I outline a theory of such nonlinear screening of Coulomb disorder in three-dimensional Dirac systems, and present results for the typical magnitude of the disorder potential, the corresponding density of states, and the size and density of electron/hole puddles. The resulting conductivity is also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goswami, Pallab; Goldman, Hart; Raghu, S.

Metallic phases have been observed in several disordered two-dimensional (2D) systems, including thin films near superconductor-insulator transitions and quantum Hall systems near plateau transitions. The existence of 2D metallic phases at zero temperature generally requires an interplay of disorder and interaction effects. Consequently, experimental observations of 2D metallic behavior have largely defied explanation. We formulate a general stability criterion for strongly interacting, massless Dirac fermions against disorder, which describe metallic ground states with vanishing density of states. We show that (2+1)-dimensional quantum electrodynamics (QED 3) with a large, even number of fermion flavors remains metallic in the presence of weakmore » scalar potential disorder due to the dynamic screening of disorder by gauge fluctuations. In conclusion, we also show that QED 3 with weak mass disorder exhibits a stable, dirty metallic phase in which both interactions and disorder play important roles.« less

Temperature Dependence of the Upper Critical Field in Disordered Hubbard Model with Attraction

NASA Astrophysics Data System (ADS)

Kuchinskii, E. Z.; Kuleeva, N. A.; Sadovskii, M. V.

2017-12-01

We study disorder effects upon the temperature behavior of the upper critical magnetic field in an attractive Hubbard model within the generalized DMFT+Σ approach. We consider the wide range of attraction potentials U—from the weak coupling limit, where superconductivity is described by BCS model, up to the strong coupling limit, where superconducting transition is related to Bose-Einstein condensation (BEC) of compact Cooper pairs, formed at temperatures significantly higher than superconducting transition temperature, as well as the wide range of disorder—from weak to strong, when the system is in the vicinity of Anderson transition. The growth of coupling strength leads to the rapid growth of H c2( T), especially at low temperatures. In BEC limit and in the region of BCS-BEC crossover H c2( T), dependence becomes practically linear. Disordering also leads to the general growth of H c2( T). In BCS limit of weak coupling increasing disorder lead both to the growth of the slope of the upper critical field in the vicinity of the transition point and to the increase of H c2( T) in the low temperature region. In the limit of strong disorder in the vicinity of the Anderson transition localization corrections lead to the additional growth of H c2( T) at low temperatures, so that the H c2( T) dependence becomes concave. In BCS-BEC crossover region and in BEC limit disorder only slightly influences the slope of the upper critical field close to T c . However, in the low temperature region H c2 ( T may significantly grow with disorder in the vicinity of the Anderson transition, where localization corrections notably increase H c2 ( T = 0) also making H c2( T) dependence concave.

Dynamics of the Random Field Ising Model

NASA Astrophysics Data System (ADS)

Xu, Jian

The Random Field Ising Model (RFIM) is a general tool to study disordered systems. Crackling noise is generated when disordered systems are driven by external forces, spanning a broad range of sizes. Systems with different microscopic structures such as disordered mag- nets and Earth's crust have been studied under the RFIM. In this thesis, we investigated the domain dynamics and critical behavior in two dipole-coupled Ising ferromagnets Nd2Fe14B and LiHoxY 1-xF4. With Tc well above room temperature, Nd2Fe14B has shown reversible disorder when exposed to an external transverse field and crosses between two universality classes in the strong and weak disorder limits. Besides tunable disorder, LiHoxY1-xF4 has shown quantum tunneling effects arising from quantum fluctuations, providing another mechanism for domain reversal. Universality within and beyond power law dependence on avalanche size and energy were studied in LiHo0.65Y0.35 F4.

Elephants in Pyjamas: Testing the Weak Central Coherence Account of Autism Spectrum Disorders Using a Syntactic Disambiguation Task

ERIC Educational Resources Information Center

Riches, N. G.; Loucas, T.; Baird, G.; Charman, T.; Simonoff, E.

2016-01-01

According to the weak central coherence (CC) account individuals with autism spectrum disorders (ASD) exhibit enhanced local processing and weak part-whole integration. CC was investigated in the verbal domain. Adolescents, recruited using a 2 (ASD status) by 2 (language impairment status) design, completed an aural forced choice comprehension…

Weak localization of magnons in chiral magnets

NASA Astrophysics Data System (ADS)

Evers, Martin; Müller, Cord A.; Nowak, Ulrich

2018-05-01

We report on the impact of the Dzyaloshinskii-Moriya interaction on the coherent backscattering of spin waves in a disordered magnetic material. This interaction breaks the inversion symmetry of the spin-wave dispersion relation, such that ωk=ω2 KI-k≠ω-k , where KI is related to the Dzyaloshinskii-Moriya vectors. The nonequivalence of k and -k also means that time-reversal symmetry is broken. As a result of numerical investigations we find that the backscattering peak of a wave packet with initial wave vector k0 shifts from -k0 to 2 KI-k0 , such that the backscattering wave vector and the initial wave vector are in general no longer antiparallel. The shifted coherence condition is explained by a diagrammatic approach and opens up an avenue to measure sign and magnitude of the Dzyaloshinskii-Moriya interaction in weakly disordered chiral magnets. Surprisingly, although time-reversal symmetry is broken, our system shows coherent backscattering as a manifestation of weak localization, which is due to the fact that reciprocity is still preserved.

Diffractive paths for weak localization in quantum billiards

NASA Astrophysics Data System (ADS)

Březinová, Iva; Stampfer, Christoph; Wirtz, Ludger; Rotter, Stefan; Burgdörfer, Joachim

2008-04-01

We study the weak-localization effect in quantum transport through a clean ballistic cavity with regular classical dynamics. We address the question which paths account for the suppression of conductance through a system where disorder and chaos are absent. By exploiting both quantum and semiclassical methods, we unambiguously identify paths that are diffractively backscattered into the cavity (when approaching the lead mouths from the cavity interior) to play a key role. Diffractive scattering couples transmitted and reflected paths and is thus essential to reproduce the weak-localization peak in reflection and the corresponding antipeak in transmission. A comparison of semiclassical calculations featuring these diffractive paths yields good agreement with full quantum calculations and experimental data. Our theory provides system-specific predictions for the quantum regime of few open lead modes and can be expected to be relevant also for mixed as well as chaotic systems.

Superfluid H3e in globally isotropic random media

NASA Astrophysics Data System (ADS)

Ikeda, Ryusuke; Aoyama, Kazushi

2009-02-01

Recent theoretical and experimental studies of superfluid H3e in aerogels with a global anisotropy created, e.g., by an external stress have definitely shown that the A -like phase with an equal-spin pairing in such aerogel samples is in the Anderson-Brinkman-Morel (ABM) (or axial) pairing state. In this paper, the A -like phase of superfluid H3e in globally isotropic aerogel is studied in detail by assuming a weakly disordered system in which singular topological defects are absent. Through calculation of the free energy, a disordered ABM state is found to be the best candidate of the pairing state of the globally isotropic A -like phase. Further, it is found through a one-loop renormalization-group calculation that the coreless continuous vortices (or vortex-Skyrmions) are irrelevant to the long-distance behavior of disorder-induced textures, and that the superfluidity is maintained in spite of lack of the conventional superfluid long-range order. Therefore, the globally isotropic A -like phase at weak disorder is, like in the case with a globally stretched anisotropy, a glass phase with the ABM pairing and shows superfluidity.

Dynamical Properties of Disordered Systems.

DTIC Science & Technology

1984-05-21

34Frequency dependence of the conductivity in presence of an electric field in one dimension: Weak disorder limit", by B. Derrida and R. Orbach, Phys...strips) of B. Derrida and J. Vannimenus (submitted for publication, 1982) finds t = 1.28, in close accord with the above consequence (t = 1.264) of...obtained ver’ glasses should exhibit such a length, roughly independent recently for percolating networks by B. Derrida . R. Or- of the character of their

Finite-temperature behavior of a classical spin-orbit-coupled model for YbMgGaO4 with and without bond disorder

NASA Astrophysics Data System (ADS)

Parker, Edward; Balents, Leon

2018-05-01

We present the results of finite-temperature classical Monte Carlo simulations of a strongly spin-orbit-coupled nearest-neighbor triangular-lattice model for the candidate U (1 ) quantum spin liquid YbMgGaO4 at large system sizes. We find a single continuous finite-temperature stripe-ordering transition with slowly diverging heat capacity that completely breaks the sixfold ground-state degeneracy, despite the absence of a known conformal field theory describing such a transition. We also simulate the effect of random-bond disorder in the model, and find that even weak bond disorder destroys the transition by fragmenting the system into very large domains—possibly explaining the lack of observed ordering in the real material. The Imry-Ma argument only partially explains this fragility to disorder, and we extend the argument with a physical explanation for the preservation of our system's time-reversal symmetry even under a disorder model that preserves the same symmetry.

Low eigenvalues of the entanglement Hamiltonian, localization length, and rare regions in one-dimensional disordered interacting systems

NASA Astrophysics Data System (ADS)

Berkovits, Richard

2018-03-01

The properties of the low-lying eigenvalues of the entanglement Hamiltonian and their relation to the localization length of a disordered interacting one-dimensional many-particle system are studied. The average of the first entanglement Hamiltonian level spacing is proportional to the ground-state localization length and shows the same dependence on the disorder and interaction strength as the localization length. This is the result of the fact that entanglement is limited to distances of order of the localization length. The distribution of the first entanglement level spacing shows a Gaussian-type behavior as expected for level spacings much larger than the disorder broadening. For weakly disordered systems (localization length larger than sample length), the distribution shows an additional peak at low-level spacings. This stems from rare regions in some samples which exhibit metalliclike behavior of large entanglement and large particle-number fluctuations. These intermediate microemulsion metallic regions embedded in the insulating phase are discussed.

Particle-hole symmetry, many-body localization, and topological edge modes

NASA Astrophysics Data System (ADS)

Vasseur, Romain; Friedman, Aaron J.; Parameswaran, S. A.; Potter, Andrew C.

We study the excited states of interacting fermions in one dimension with particle-hole symmetric disorder (equivalently, random-bond XXZ chains) using a combination of renormalization group methods and exact diagonalization. Absent interactions, the entire many-body spectrum exhibits infinite-randomness quantum critical behavior with highly degenerate excited states. We show that though interactions are an irrelevant perturbation in the ground state, they drastically affect the structure of excited states: even arbitrarily weak interactions split the degeneracies in favor of thermalization (weak disorder) or spontaneously broken particle-hole symmetry, driving the system into a many-body localized spin glass phase (strong disorder). In both cases, the quantum critical properties of the non-interacting model are destroyed, either by thermal decoherence or spontaneous symmetry breaking. This system then has the interesting and counterintuitive property that edges of the many-body spectrum are less localized than the center of the spectrum. We argue that our results rule out the existence of certain excited state symmetry-protected topological orders. Supported by the Gordon and Betty Moore Foundation's EPiQS Initiative (Grant GBMF4307 (ACP), the Quantum Materials Program at LBNL (RV), NSF Grant DMR-1455366 and UCOP Research Catalyst Award No. CA-15-327861 (SAP).

Survival and weak chaos.

PubMed

Nee, Sean

2018-05-01

Survival analysis in biology and reliability theory in engineering concern the dynamical functioning of bio/electro/mechanical units. Here we incorporate effects of chaotic dynamics into the classical theory. Dynamical systems theory now distinguishes strong and weak chaos. Strong chaos generates Type II survivorship curves entirely as a result of the internal operation of the system, without any age-independent, external, random forces of mortality. Weak chaos exhibits (a) intermittency and (b) Type III survivorship, defined as a decreasing per capita mortality rate: engineering explicitly defines this pattern of decreasing hazard as 'infant mortality'. Weak chaos generates two phenomena from the normal functioning of the same system. First, infant mortality- sensu engineering-without any external explanatory factors, such as manufacturing defects, which is followed by increased average longevity of survivors. Second, sudden failure of units during their normal period of operation, before the onset of age-dependent mortality arising from senescence. The relevance of these phenomena encompasses, for example: no-fault-found failure of electronic devices; high rates of human early spontaneous miscarriage/abortion; runaway pacemakers; sudden cardiac death in young adults; bipolar disorder; and epilepsy.

Survival and weak chaos

PubMed Central

2018-01-01

Survival analysis in biology and reliability theory in engineering concern the dynamical functioning of bio/electro/mechanical units. Here we incorporate effects of chaotic dynamics into the classical theory. Dynamical systems theory now distinguishes strong and weak chaos. Strong chaos generates Type II survivorship curves entirely as a result of the internal operation of the system, without any age-independent, external, random forces of mortality. Weak chaos exhibits (a) intermittency and (b) Type III survivorship, defined as a decreasing per capita mortality rate: engineering explicitly defines this pattern of decreasing hazard as ‘infant mortality’. Weak chaos generates two phenomena from the normal functioning of the same system. First, infant mortality—sensu engineering—without any external explanatory factors, such as manufacturing defects, which is followed by increased average longevity of survivors. Second, sudden failure of units during their normal period of operation, before the onset of age-dependent mortality arising from senescence. The relevance of these phenomena encompasses, for example: no-fault-found failure of electronic devices; high rates of human early spontaneous miscarriage/abortion; runaway pacemakers; sudden cardiac death in young adults; bipolar disorder; and epilepsy. PMID:29892407

Single-Particle Mobility Edge in a One-Dimensional Quasiperiodic Optical Lattice

NASA Astrophysics Data System (ADS)

Lüschen, Henrik P.; Scherg, Sebastian; Kohlert, Thomas; Schreiber, Michael; Bordia, Pranjal; Li, Xiao; Das Sarma, S.; Bloch, Immanuel

2018-04-01

A single-particle mobility edge (SPME) marks a critical energy separating extended from localized states in a quantum system. In one-dimensional systems with uncorrelated disorder, a SPME cannot exist, since all single-particle states localize for arbitrarily weak disorder strengths. However, in a quasiperiodic system, the localization transition can occur at a finite detuning strength and SPMEs become possible. In this Letter, we find experimental evidence for the existence of such a SPME in a one-dimensional quasiperiodic optical lattice. Specifically, we find a regime where extended and localized single-particle states coexist, in good agreement with theoretical simulations, which predict a SPME in this regime.

Optical and thermal-transport properties of an inhomogeneous d-wave superconductor.

PubMed

Atkinson, W A; Hirschfeld, P J

2002-05-06

We calculate transport properties of disordered 2D d-wave superconductors from solutions of the Bogoliubov-de Gennes equations, and show that weak localization effects give rise to a finite-frequency peak in the optical conductivity similar to that observed in experiments on disordered cuprates. At low energies, order parameter inhomogeneities induce linear and quadratic temperature dependencies in microwave and thermal conductivities respectively, and appear to drive the system towards a quasiparticle insulating phase.

Glassy phases and driven response of the phase-field-crystal model with random pinning.

PubMed

Granato, E; Ramos, J A P; Achim, C V; Lehikoinen, J; Ying, S C; Ala-Nissila, T; Elder, K R

2011-09-01

We study the structural correlations and the nonlinear response to a driving force of a two-dimensional phase-field-crystal model with random pinning. The model provides an effective continuous description of lattice systems in the presence of disordered external pinning centers, allowing for both elastic and plastic deformations. We find that the phase-field crystal with disorder assumes an amorphous glassy ground state, with only short-ranged positional and orientational correlations, even in the limit of weak disorder. Under increasing driving force, the pinned amorphous-glass phase evolves into a moving plastic-flow phase and then, finally, a moving smectic phase. The transverse response of the moving smectic phase shows a vanishing transverse critical force for increasing system sizes.

Collective Transport Properties of Driven Skyrmions with Random Disorder

NASA Astrophysics Data System (ADS)

Reichhardt, C.; Ray, D.; Reichhardt, C. J. Olson

2015-05-01

We use particle-based simulations to examine the static and driven collective phases of Skyrmions interacting with random quenched disorder. We show that nondissipative effects due to the Magnus term reduce the depinning threshold and strongly affect the Skyrmion motion and the nature of the dynamic phases. The quenched disorder causes the Hall angle to become drive dependent in the moving Skyrmion phase, while different flow regimes produce distinct signatures in the transport curves. For weak disorder, the Skyrmions form a pinned crystal and depin elastically, while for strong disorder the system forms a pinned amorphous state that depins plastically. At high drives the Skyrmions can dynamically reorder into a moving crystal, with the onset of reordering determined by the strength of the Magnus term.

[Esophageal motility characteristics of refractory heartburn: a study based on high resolution manometry and 24 hour pH-impedance monitoring].

PubMed

Wang, Kun; Duan, Liping; Xia, Zhiwei; Xu, Zhijie; Ge, Ying

2014-09-16

To analyze the esophageal motility characteristics of refractory heartburn with different reflux patterns and preliminarily clarify the roles of esophageal disorder in refractory heartburn. A total of 176 refractory heartburn patients were enrolled from 2009 to 2013. After gastroscopy and 24 hour pH-impedance monitoring, they were divided into 4 groups of reflux esophagitis (RE, n = 29), non-erosive reflux disease with acid reflux (NERD-acid, n = 51), NERD with weakly acidic reflux (NERD-weakly acid, n = 51) and non-reflux associated heartburn (n = 45). All subjects undertake high resolution manometry test and their esophageal motility functions were analyzed by the Chicago classification criteria 2012. Among them, 60.23% (106/176) patients presented esophageal motility disorders. And 42.61% (75/176) fulfilled the criteria of weak peristalsis, 7.39% (13/176) distal esophageal spasm, 4.55% (8/176) rapid contraction, 3.98% (7/176) EGJ outflow obstruction, 1.14% (2/176) hiatus hernia and 1 Jackhammer esophagus. The detection rates of esophageal motility disorder were similar among 4 groups and weak peristalsis was the most common disorder in all groups (41.38% in RE, 37.25% in NERD-acid patients, 54.90% in NERD-weakly acid and 35.56% in non-reflux associated heartburn patients). However, hypertensive motility disorders in non-reflux associated heartburn group (31.11%, 14/45) were more than GERD subgroups (11.45%, 15/131) (P < 0.05) . The relax ratio of low esophagus sphincter (LES) in GERD subgroups were higher than that in non-reflux associated heartburn patients. And the relax ratio of NERD-weakly acid was significantly higher than that in non-reflux associated heartburn patients (65% (50%-80%) vs 58% (42%-67%) , P < 0.05). The integrated relaxation pressure in GERD subgroups were lower than that of non-reflux associated heartburn patients without significant differences (P > 0.05). Esophageal weak peristalsis is one of the most common motility disorders in refractory heartburn patients, and esophageal hypertensive motility disorders are common in non-reflux associated heartburn patients. Esophageal manometry is necessary for the diagnosis and treatment of refractory heartburn.

Gestalt Imagery: A Critical Factor in Language Comprehension.

ERIC Educational Resources Information Center

Bell, Nanci

1991-01-01

Lack of gestalt imagery (the ability to create imaged wholes) can contribute to language comprehension disorder characterized by weak reading comprehension, weak oral language comprehension, weak oral language expression, weak written language expression, difficulty following directions, and a weak sense of humor. Sequential stimulation using an…

Weak Localization of Light in a Disordered Microcavity

NASA Astrophysics Data System (ADS)

Gurioli, M.; Bogani, F.; Cavigli, L.; Gibbs, H.; Khitrova, G.; Wiersma, D. S.

2005-05-01

We report the observation of weak localization of light in a semiconductor microcavity. The intrinsic disorder in a microcavity leads to multiple scattering and hence to static speckle. We show that averaging over realizations of the disorder reveals a coherent backscattering cone that has a coherent enhancement factor ≥2, as required by reciprocity. The coherent backscattering cone is observed along a ring-shaped pattern due to confinement by the microcavity.

[Pathogenesis of hypophosphatemia].

PubMed

Takeuchi, Yasuhiro

2016-02-01

Chronic hypophosphatemia is seriously involved in several disorders of musculoskeletal system. Symptoms of patients are usually non-specific, such as pain with or without muscle weakness on lower extremities and are often hard to be correctly diagnosed. It is clinically important for physicians to understand pathogenesis and clinical features of hypophosphatemia and its related diseases.

Beyond the DSM-IV: Assumptions, Alternatives, and Alterations

ERIC Educational Resources Information Center

Lopez, Shane J.; Edwards, Lisa M.; Pedrotti, Jennifer Teramoto; Prosser, Ellie C.; LaRue, Stephanie; Spalitto, Susan Vehige; Ulven, Jon C.

2006-01-01

Current diagnostic processes reflect the limitations and utility of the framework of the "Diagnostic and Statistical Manual of Mental Disorders" (4th ed.; DSM-IV; American Psychiatric Association, 1994). Clinical information in the DSM-IV's 5-axis system almost exclusively focuses on weaknesses and pathology and is summarized in a flawed…

Childhood Multiple Sclerosis: A Review

ERIC Educational Resources Information Center

Waldman, Amy; O'Connor, Erin; Tennekoon, Gihan

2006-01-01

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS) that is increasingly recognized as a disease that affects children. Similar to adult-onset MS, children present with visual and sensory complaints, as well as weakness, spasticity, and ataxia. A lumbar puncture can be helpful in diagnosing MS when…

Literature Review of Cognitive Neuroscience and Anorexia Nervosa.

PubMed

Reville, Marie-Claire; O'Connor, Lorna; Frampton, Ian

2016-02-01

Studies published between the beginning of 2013 and May 2015 on the neuropsychological functioning of patients with anorexia nervosa compared with healthy participants framed in the context of the Research Domain Criteria matrix identifies evidence for functional differences in three domains: Negative Valance Systems-negative attentional biases and lack of neural responsivity to hunger; Cognitive Systems-limited congruence between clinical and cognitive performance, poorer non-verbal than verbal performance, altered attentional styles to disorder related stimuli, perceptual processing impairment in discriminating body images, weaknesses in central coherence, set shifting weaknesses at low weight status, decision-making weaknesses, and greater neural resources required for working memory; Systems for Social Processes-patients appear to have a different attentional response to faces, and perception and understanding of self and others. Hence, there is evidence to suggest that patients with anorexia nervosa have a specific neuropsychological performance style across tasks in three domains of functioning. Some current controversies and areas for future development are identified.

Disorder-induced topological phase transitions in two-dimensional spin-orbit coupled superconductors

PubMed Central

Qin, Wei; Xiao, Di; Chang, Kai; Shen, Shun-Qing; Zhang, Zhenyu

2016-01-01

Normal superconductors with Rashba spin-orbit coupling have been explored as candidate systems of topological superconductors. Here we present a comparative theoretical study of the effects of different types of disorder on the topological phases of two-dimensional Rashba spin-orbit coupled superconductors. First, we show that a topologically trivial superconductor can be driven into a chiral topological superconductor upon diluted doping of isolated magnetic disorder, which close and reopen the quasiparticle gap of the paired electrons in a nontrivial manner. Secondly, the superconducting nature of a topological superconductor is found to be robust against Anderson disorder, but the topological nature is not, converting the system into a topologically trivial state even in the weak scattering limit. These topological phase transitions are distinctly characterized by variations in the topological invariant. We discuss the central findings in connection with existing experiments, and provide new schemes towards eventual realization of topological superconductors. PMID:27991541

Disorder-induced topological phase transitions in two-dimensional spin-orbit coupled superconductors

NASA Astrophysics Data System (ADS)

Qin, Wei; Xiao, Di; Chang, Kai; Shen, Shun-Qing; Zhang, Zhenyu

2016-12-01

Normal superconductors with Rashba spin-orbit coupling have been explored as candidate systems of topological superconductors. Here we present a comparative theoretical study of the effects of different types of disorder on the topological phases of two-dimensional Rashba spin-orbit coupled superconductors. First, we show that a topologically trivial superconductor can be driven into a chiral topological superconductor upon diluted doping of isolated magnetic disorder, which close and reopen the quasiparticle gap of the paired electrons in a nontrivial manner. Secondly, the superconducting nature of a topological superconductor is found to be robust against Anderson disorder, but the topological nature is not, converting the system into a topologically trivial state even in the weak scattering limit. These topological phase transitions are distinctly characterized by variations in the topological invariant. We discuss the central findings in connection with existing experiments, and provide new schemes towards eventual realization of topological superconductors.

Anderson Localization from the Berry-Curvature Interchange in Quantum Anomalous Hall Systems

NASA Astrophysics Data System (ADS)

Qiao, Zhenhua; Han, Yulei; Zhang, Lei; Wang, Ke; Deng, Xinzhou; Jiang, Hua; Yang, Shengyuan A.; Wang, Jian; Niu, Qian

2016-07-01

We theoretically investigate the localization mechanism of the quantum anomalous Hall effect (QAHE) in the presence of spin-flip disorders. We show that the QAHE stays quantized at weak disorders, then enters a Berry-curvature mediated metallic phase at moderate disorders, and finally goes into the Anderson insulating phase at strong disorders. From the phase diagram, we find that at the charge neutrality point although the QAHE is most robust against disorders, the corresponding metallic phase is much easier to be localized into the Anderson insulating phase due to the interchange of Berry curvatures carried, respectively, by the conduction and valence bands. In the end, we provide a phenomenological picture related to the topological charges to better understand the underlying physical origin of the QAHE Anderson localization.

Anderson Localization from the Berry-Curvature Interchange in Quantum Anomalous Hall Systems

NASA Astrophysics Data System (ADS)

Han, Yulei; Qiao, Zhenhua

In this talk, we theoretically investigate the localization mechanism of the quantum anomalous Hall effect (QAHE) in the presence of spin-flip disorders. We show that the QAHE stays quantized at weak disorders, then enters a Berry-curvature mediated metallic phase at moderate disorders, and finally goes into the Anderson insulating phase at strong disorders. From the phase diagram, we find that at the charge neutrality point although the QAHE is most robust against disorders, the corresponding metallic phase is much easier to be localized into the Anderson insulating phase due to the interchange of Berry curvatures carried, respectively, by the conduction and valence bands. In the end, we provide a phenomenological picture related to the topological charges to better understand the underlying physical origin of the QAHE Anderson localization.

Diffusion and transport in locally disordered driven lattices

NASA Astrophysics Data System (ADS)

Wulf, Thomas; Okupnik, Alexander; Schmelcher, Peter

2016-09-01

We study the effect of disorder on the particle density evolution in a classical Hamiltonian driven lattice setup. If the disorder is localized within a finite sub-domain of the lattice, the emergence of strong tails in the density distribution which even increases towards larger positions is shown, thus yielding a highly non-Gaussian particle density evolution. As the key underlying mechanism, we identify the conversion between different components of the unperturbed systems mixed phase space which is induced by the disorder. Based on the introduction of individual conversion rates between chaotic and regular components, a theoretical model is developed which correctly predicts the scaling of the particle density. The effect of disorder on the transport properties is studied where a significant enhancement of the transport for cases of localized disorder is shown, thereby contrasting strongly the merely weak modification of the transport for global disorder.

The Weak Coherence Account: Detail-Focused Cognitive Style in Autism Spectrum Disorders

ERIC Educational Resources Information Center

Happe, Francesca; Frith, Uta

2006-01-01

"Weak central coherence" refers to the detail-focused processing style proposed to characterise autism spectrum disorders (ASD). The original suggestion of a core deficit in central processing resulting in failure to extract global form/meaning, has been challenged in three ways. First, it may represent an outcome of superiority in local…

Complicating autoimmune diseases in myasthenia gravis: a review

PubMed Central

Nacu, Aliona; Andersen, Jintana Bunpan; Lisnic, Vitalie; Owe, Jone Furlund; Gilhus, Nils Erik

2015-01-01

Abstract Myasthenia gravis (MG) is a rare autoimmune disease of skeletal muscle endplates. MG subgroup is relevant for comorbidity, but usually not accounted for. MG patients have an increased risk for complicating autoimmune diseases, most commonly autoimmune thyroid disease, systemic lupus erythematosus and rheumatoid arthritis. In this review, we present concomitant autoimmune disorders associated with the different MG subgroups, and show how this influences treatment and prognosis. Concomitant MG should always be considered in patients with an autoimmune disorder and developing new neuromuscular weakness, fatigue or respiratory failure. When a second autoimmune disorder is suspected, MG should be included as a differential diagnosis. PMID:25915571

Lifshitz phase: the microscopic structure of aqueous and ethanol mixtures of 1,n-diols.

PubMed

Požar, Martina; Perera, Aurélien

2017-06-14

We study binary mixtures of ethylene glycol and 1,3-propandiol with water or ethanol using computer simulations. Despite strong hydrogen bonding tendencies between all these molecules, we find that these mixtures are surprisingly homogeneous, in contrast to the strong micro-heterogeneity found in aqueous ethanol mixtures. The aqueous diol mixtures are found to be close to ideal mixtures, with near-ideal Kirkwood-Buff integrals. Ethanol-diol mixtures show weak non-ideality. The origin of this unexpected randomness is due to the fact that the two hydrogen bonding hydroxyl groups of the 1,n-diol are bound by the neutral alkyl bond, which prevents the micro-segregation of the different types of hydroxyl groups. These findings suggest that random disorder can arise in the presence of strong interactions - in contrast to the usual picture of random disorder due to weak interactions between the components. They point to the important role of molecular topology in tuning concentration fluctuations in complex liquids. We propose and justify herein the name of Lifshitz phases to designate such types of disordered systems.

Localization Transport in Granular and Nanoporous Carbon Systems.

NASA Astrophysics Data System (ADS)

Fung, Alex Weng Pui

Porous carbon materials have long since been used in industry to make capacitors and adsorption agents because of their high specific surface area. Although their adsorption properties have been extensively studied, we have not seen the same vigor in the investigation of their physical properties, which are important not only for providing complementary characterization methods, but also for understanding the physics which underlies the manufacturing process and motivates intelligent design of these materials. The study of the new physics in these novel nanoporous materials also straddles the scientific forefronts of nanodimensional and disordered systems. In this thesis, we study the structural and electrical properties of two nanoporous carbons, namely activated carbon fibers and carbon aerogels. Specifically, we perform Raman scattering, x-ray diffraction, magnetic susceptibility, electrical transport and magnetotransport experiments. Results from other experiments reported in the literature or communicated to us by our collaborators, such as porosity and surface area measurements by adsorption methods, electron spin resonance, transmission electron microscopy, mechanical properties measurements and so on, are also frequently used in this thesis for additional characterization information. By correlating all the relevant results, we obtain the structure -property relationships in these nanoporous materials. This study shows that the transport properties of these porous materials can be used on one hand for sensitive characterization of complex materials, and on the other hand, for observing interesting and unusual physical phenomena. For example, as-prepared nanoporous carbon systems, exhibit in their low-temperature electrical conductivity a universal temperature dependence which is characteristic of a granular metallic system, despite their morphological differences. By studying further the magnetoresistance in these carbon materials, it is found that the variable-range hopping mechanism cannot be totally disregarded in the understanding of the low-temperature conduction process in some granular metals having a similar morphology. In the transport study of the heat-treated activated carbon fibers, the surprising observation of a negative magnetoresistance at room temperature has also provided some insight into the weak localization phenomenon in the percolation limit. In particular, the effects of anomalous diffusion in a percolating system is now included in the calculations of the weak-localization corrections to the conductivity and magnetoresistance, yielding a new temperature dependence of the dephasing distance. These localization phenomena in the nanoporous carbon structures studied here are mostly understandable in terms of the existing theories for disordered systems, but their detailed interpretations often indicate problems and shortcomings in some of these theories, at times because the physical properties of the nanoporous carbon materials studied here are unique among disordered materials. Hence, nanoporous carbons belong to a distinct class of disordered systems in their own rights. In the field of transport in disordered systems, porous media also seem to have been an oversight of the general research community, although theoretical percolation studies have often touched upon systems with similar morphologies. This thesis presents a study of the transport behavior in nanoporous carbons over the full spectrum of disorder, controlled by heat treatment, starting from the strong localization regime, then crossing the metal-insulator transition, and finally to the weak localization limit. In each regime of disorder, the existing theories are either adapted, and when necessary, extended to explain the observed transport behavior in these fascinating materials. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-1690.).

A high-efficiency spin polarizer based on edge and surface disordered silicene nanoribbons

NASA Astrophysics Data System (ADS)

Xu, Ning; Zhang, Haiyang; Wu, Xiuqiang; Chen, Qiao; Ding, Jianwen

2018-07-01

Using the tight-binding formalism, we explore the effect of weak disorder upon the conductance of zigzag edge silicene nanoribbons (SiNRs), in the limit of phase-coherent transport. We find that the fashion of the conductance varies with disorder, and depends strongly on the type of disorder. Conductance dips are observed at the Van Hove singularities, owing to quasilocalized states existing in surface disordered SiNRs. A conductance gap is observed around the Fermi energy for both edge and surface disordered SiNRs, because edge states are localized. The average conductance of the disordered SiNRs decreases exponentially with the increase of disorder, and finally tends to disappear. The near-perfect spin polarization can be realized in SiNRs with a weak edge or surface disorder, and also can be attained by both the local electric field and the exchange field.

Brief Report: Generalization Weaknesses in Verbally Fluent Children and Adolescents with Autism Spectrum Disorder

ERIC Educational Resources Information Center

de Marchena, Ashley B.; Eigsti, Inge-Marie; Yerys, Benjamin E.

2015-01-01

Individuals with autism spectrum disorder (ASD) have difficulty generalizing--i.e., relating new stimuli to past experiences. Few experimental studies have addressed this weakness, despite its impact on intervention effects. In a reanalysis of data (de Marchena et al. "Cognition" 119(1):96-113, 2011), we tested a novel form of…

Continuing Development of the Vulnerability Model

DTIC Science & Technology

1977-02-01

likely to involve an entirely differ- ent toxic mechanism , brought on by exposure to higher concentrations and affecting the central nervous system... mechanisms with quite dif- ferent syndromes . One is its effect as a depressant of the central ŕ nervous system, in which it acts like many other...other sensory disorder , weakness, muscular incoordination, and epilepsy -- like seizures. All these symptoms have been seen to per- 4 •sist. The

Disorder-assisted quantum transport in suboptimal decoherence regimes

PubMed Central

Novo, Leonardo; Mohseni, Masoud; Omar, Yasser

2016-01-01

We investigate quantum transport in binary tree structures and in hypercubes for the disordered Frenkel-exciton Hamiltonian under pure dephasing noise. We compute the energy transport efficiency as a function of disorder and dephasing rates. We demonstrate that dephasing improves transport efficiency not only in the disordered case, but also in the ordered one. The maximal transport efficiency is obtained when the dephasing timescale matches the hopping timescale, which represent new examples of the Goldilocks principle at the quantum scale. Remarkably, we find that in weak dephasing regimes, away from optimal levels of environmental fluctuations, the average effect of increasing disorder is to improve the transport efficiency until an optimal value for disorder is reached. Our results suggest that rational design of the site energies statistical distributions could lead to better performances in transport systems at nanoscale when their natural environments are far from the optimal dephasing regime. PMID:26726133

Equilibrium phases of dipolar lattice bosons in the presence of random diagonal disorder

NASA Astrophysics Data System (ADS)

Zhang, C.; Safavi-Naini, A.; Capogrosso-Sansone, B.

2018-01-01

Ultracold gases offer an unprecedented opportunity to engineer disorder and interactions in a controlled manner. In an effort to understand the interplay between disorder, dipolar interactions, and quantum degeneracy, we study two-dimensional hard-core dipolar lattice bosons in the presence of on-site bound disorder. Our results are based on large-scale path-integral quantum Monte Carlo simulations by the worm algorithm. We study the ground-state phase diagram at a fixed half-integer filling factor for which the clean system is either a superfluid at a lower dipolar interaction strength or a checkerboard solid at a larger dipolar interaction strength. We find that, even for weak dipolar interactions, superfluidity is destroyed in favor of a Bose glass at a relatively low disorder strength. Interestingly, in the presence of disorder, superfluidity persists for values of the dipolar interaction strength for which the clean system is a checkerboard solid. At a fixed disorder strength, as the dipolar interaction is increased, superfluidity is destroyed in favor of a Bose glass. As the interaction is further increased, the system eventually develops extended checkerboard patterns in the density distribution. Due to the presence of disorder, though, grain boundaries and defects, responsible for a finite residual compressibility, are present in the density distribution. Finally, we study the robustness of the superfluid phase against thermal fluctuations.

Proximal weakness of lower limbs as the sole presentation of hyperthyroidism: report of one case.

PubMed

Chen, Chu-Chin; Chiu, Pao-Chin; Shih, Chen-Houng; Hsieh, Kai-Sheng

2005-01-01

Most children with acute or chronic flaccid limb weakness have a disorder of motor unit. However, it is very important to exclude cerebral or other upper motor neuron disorders before we approach such patients as pure muscle disorders. In general, neuropathy results in distal limb weakness, myopathy manifests with proximal weakness. There are exceptions, however. Accurate diagnosis in this wide array of disorders is dependent on a careful clinical assessment followed by the appropriate investigations. Here we report a 14-year-old girl who presented with progressive difficulty in rising up from the floor for one month. Neurological examination revealed an obese, clumsy but clear girl with stable vital signs. The muscle power of neck and upper limbs was normal. There was positive Gower sign, but the toe and heel gaits were acceptable. The initial blood work and motor/sensory nerve conduction velocity were unremarkable. Further study for thyroid function showed a hyperthyroid state. The proximal myopathy recovered soon after medical treatment. There were no other symptoms, and signs indicating hyperthyroidism and proximal myopathy of lower limbs was the isolated clinical feature. Hyperthyroid myopathy is common in hyperthyroidism, but is unusual as the sole presenting symptom.

[Difficulties with diagnosis of fibromyalgia: case report].

PubMed

Atarowska, Magdalena; Samborski, Włodzimierz

2006-01-01

We present a case of a 33-year-old woman with nonspecific systemic symptoms (fatigue, weakness), widespread pains, sleep disorders, morning stiffness, accompanied by symptoms from the autonomic nervous system (chest pain, digestive tract disorders, hyperesthesia of the skin, dizziness, paresthesia with a feeling of coldness in hands and feet, excessive sweating, breath problems, palpitations). The diagnostic process was difficult and it took a long time to establish the diagnosis partly because of problems in cooperating with this patient. During several years, the woman was hospitalized at several specialist departments, underwent many consultations, laboratory tests, and imaging studies. Finally, fibromyalgia was diagnosed. Treatment was implemented with good results improving the quality of life of this patient.

Investigation of Poor Academic Achievement in Children with Duchenne Muscular Dystrophy

ERIC Educational Resources Information Center

Hinton, V. J.; De Vivo, D. C.; Fee, R.; Goldstein, E.; Stern, Y.

2004-01-01

Duchenne Muscular Dystrophy (DMD) is a neurogenetic developmental disorder that presents with progressive muscular weakness. It is caused by a mutation in a gene that results in the absence of specific products that normally localize to muscle cells and the central nervous system (CNS). The majority of affected individuals have IQs within the…

Quench dynamics of one-dimensional interacting bosons in a disordered potential: elastic dephasing and critical speeding-up of thermalization.

PubMed

Tavora, Marco; Rosch, Achim; Mitra, Aditi

2014-07-04

The dynamics of interacting bosons in one dimension following the sudden switching on of a weak disordered potential is investigated. On time scales before quasiparticles scatter (prethermalized regime), the dephasing from random elastic forward scattering causes all correlations to decay exponentially fast, but the system remains far from thermal equilibrium. For longer times, the combined effect of disorder and interactions gives rise to inelastic scattering and to thermalization. A novel quantum kinetic equation accounting for both disorder and interactions is employed to study the dynamics. Thermalization turns out to be most effective close to the superfluid-Bose-glass critical point where nonlinearities become more and more important. The numerically obtained thermalization times are found to agree well with analytic estimates.

Disordered topological wires in a momentum-space lattice

NASA Astrophysics Data System (ADS)

Meier, Eric; An, Fangzhao; Gadway, Bryce

2017-04-01

One of the most interesting aspects of topological systems is the presence of boundary modes which remain robust in the presence of weak disorder. We explore this feature in the context of one-dimensional (1D) topological wires where staggered tunneling strengths lead to the creation of a mid-gap state in the lattice band structure. Using Bose-condensed 87Rb atoms in a 1D momentum-space lattice, we probe the robust topological character of this model when subjected to both site energy and tunneling disorder. We observe a transition to a topologically trivial phase when tailored disorder is applied, which we detect through both charge-pumping and Hamiltonian-quenching protocols. In addition, we report on efforts to probe the influence of interactions in topological momentum-space lattices.

Link prediction boosted psychiatry disorder classification for functional connectivity network

NASA Astrophysics Data System (ADS)

Li, Weiwei; Mei, Xue; Wang, Hao; Zhou, Yu; Huang, Jiashuang

2017-02-01

Functional connectivity network (FCN) is an effective tool in psychiatry disorders classification, and represents cross-correlation of the regional blood oxygenation level dependent signal. However, FCN is often incomplete for suffering from missing and spurious edges. To accurate classify psychiatry disorders and health control with the incomplete FCN, we first `repair' the FCN with link prediction, and then exact the clustering coefficients as features to build a weak classifier for every FCN. Finally, we apply a boosting algorithm to combine these weak classifiers for improving classification accuracy. Our method tested by three datasets of psychiatry disorder, including Alzheimer's Disease, Schizophrenia and Attention Deficit Hyperactivity Disorder. The experimental results show our method not only significantly improves the classification accuracy, but also efficiently reconstructs the incomplete FCN.

q Breathers in Finite Lattices: Nonlinearity and Weak Disorder

NASA Astrophysics Data System (ADS)

Ivanchenko, M. V.

2009-05-01

Nonlinearity and disorder are the recognized ingredients of the lattice vibrational dynamics, the factors that could be diminished, but never excluded. We generalize the concept of q breathers—periodic orbits in nonlinear lattices, exponentially localized in the linear mode space—to the case of weak disorder, taking the Fermi-Pasta-Ulan chain as an example. We show that these nonlinear vibrational modes remain exponentially localized near the central mode and stable, provided the disorder is sufficiently small. The instability threshold depends sensitively on a particular realization of disorder and can be modified by specifically designed impurities. Based on this sensitivity, an approach to controlling the energy flow between the modes is proposed. The relevance to other model lattices and experimental miniature arrays is discussed.

Noise fluctuations and drive dependence of the skyrmion Hall effect in disordered systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reichhardt, Charles; Olson Reichhardt, Cynthia Jane

Using a particle-based simulation model, we show that quenched disorder creates a drive-dependent skyrmion Hall effect as measured by the change in the ratiomore » $$R={V}_{\\perp }/{V}_{| | }$$ of the skyrmion velocity perpendicular (V ⊥) and parallel ($${V}_{| | }$$) to an external drive. R is zero at depinning and increases linearly with increasing drive, in agreement with recent experimental observations. At sufficiently high drives where the skyrmions enter a free flow regime, R saturates to the disorder-free limit. In addition, this behavior is robust for a wide range of disorder strengths and intrinsic Hall angle values, and occurs whenever plastic flow is present. For systems with small intrinsic Hall angles, we find that the Hall angle increases linearly with external drive, as also observed in experiment. In the weak pinning regime where the skyrmion lattice depins elastically, R is nonlinear and the net direction of the skyrmion lattice motion can rotate as a function of external drive. We show that the changes in the skyrmion Hall effect correlate with changes in the power spectrum of the skyrmion velocity noise fluctuations. The plastic flow regime is associated with $1/f$ noise, while in the regime in which R has saturated, the noise is white with a weak narrow band signal, and the noise power drops by several orders of magnitude. Finally, at low drives, the velocity noise in the perpendicular and parallel directions is of the same order of magnitude, while at intermediate drives the perpendicular noise fluctuations are much larger.« less

Noise fluctuations and drive dependence of the skyrmion Hall effect in disordered systems

DOE PAGES

Reichhardt, Charles; Olson Reichhardt, Cynthia Jane

2016-09-29

Using a particle-based simulation model, we show that quenched disorder creates a drive-dependent skyrmion Hall effect as measured by the change in the ratiomore » $$R={V}_{\\perp }/{V}_{| | }$$ of the skyrmion velocity perpendicular (V ⊥) and parallel ($${V}_{| | }$$) to an external drive. R is zero at depinning and increases linearly with increasing drive, in agreement with recent experimental observations. At sufficiently high drives where the skyrmions enter a free flow regime, R saturates to the disorder-free limit. In addition, this behavior is robust for a wide range of disorder strengths and intrinsic Hall angle values, and occurs whenever plastic flow is present. For systems with small intrinsic Hall angles, we find that the Hall angle increases linearly with external drive, as also observed in experiment. In the weak pinning regime where the skyrmion lattice depins elastically, R is nonlinear and the net direction of the skyrmion lattice motion can rotate as a function of external drive. We show that the changes in the skyrmion Hall effect correlate with changes in the power spectrum of the skyrmion velocity noise fluctuations. The plastic flow regime is associated with $1/f$ noise, while in the regime in which R has saturated, the noise is white with a weak narrow band signal, and the noise power drops by several orders of magnitude. Finally, at low drives, the velocity noise in the perpendicular and parallel directions is of the same order of magnitude, while at intermediate drives the perpendicular noise fluctuations are much larger.« less

Attractive Hubbard model with disorder and the generalized Anderson theorem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuchinskii, E. Z., E-mail: kuchinsk@iep.uran.ru; Kuleeva, N. A., E-mail: strigina@iep.uran.ru; Sadovskii, M. V., E-mail: sadovski@iep.uran.ru

Using the generalized DMFT+Σ approach, we study the influence of disorder on single-particle properties of the normal phase and the superconducting transition temperature in the attractive Hubbard model. A wide range of attractive potentials U is studied, from the weak coupling region, where both the instability of the normal phase and superconductivity are well described by the BCS model, to the strong-coupling region, where the superconducting transition is due to Bose-Einstein condensation (BEC) of compact Cooper pairs, formed at temperatures much higher than the superconducting transition temperature. We study two typical models of the conduction band with semi-elliptic and flatmore » densities of states, respectively appropriate for three-dimensional and two-dimensional systems. For the semi-elliptic density of states, the disorder influence on all single-particle properties (e.g., density of states) is universal for an arbitrary strength of electronic correlations and disorder and is due to only the general disorder widening of the conduction band. In the case of a flat density of states, universality is absent in the general case, but still the disorder influence is mainly due to band widening, and the universal behavior is restored for large enough disorder. Using the combination of DMFT+Σ and Nozieres-Schmitt-Rink approximations, we study the disorder influence on the superconducting transition temperature T{sub c} for a range of characteristic values of U and disorder, including the BCS-BEC crossover region and the limit of strong-coupling. Disorder can either suppress T{sub c} (in the weak-coupling region) or significantly increase T{sub c} (in the strong-coupling region). However, in all cases, the generalized Anderson theorem is valid and all changes of the superconducting critical temperature are essentially due to only the general disorder widening of the conduction band.« less

Disentangling weak coherence and executive dysfunction: planning drawing in autism and attention-deficit/hyperactivity disorder.

PubMed Central

Booth, Rhonda; Charlton, Rebecca; Hughes, Claire; Happé, Francesca

2003-01-01

A tendency to focus on details at the expense of configural information, 'weak coherence', has been proposed as a cognitive style in autism. In the present study we tested whether weak coherence might be the result of executive dysfunction, by testing clinical groups known to show deficits on tests of executive control. Boys with autism spectrum disorders (ASD) were compared with age- and intelligence quotient (IQ)-matched boys with attention-deficit/hyperactivity disorder (ADHD), and typically developing (TD) boys, on a drawing task requiring planning for the inclusion of a new element. Weak coherence was measured through analysis of drawing style. In line with the predictions made, the ASD group was more detail-focused in their drawings than were either ADHD or TD boys. The ASD and ADHD groups both showed planning impairments, which were more severe in the former group. Poor planning did not, however, predict detail-focus, and scores on the two aspects of the task were unrelated in the clinical groups. These findings indicate that weak coherence may indeed be a cognitive style specific to autism and unrelated to cognitive deficits in frontal functions. PMID:12639335

Neuromuscular findings in thyroid dysfunction: a prospective clinical and electrodiagnostic study.

PubMed

Duyff, R F; Van den Bosch, J; Laman, D M; van Loon, B J; Linssen, W H

2000-06-01

To evaluate neuromuscular signs and symptoms in patients with newly diagnosed hypothyroidism and hyperthyroidism. A prospective cohort study was performed in adult patients with newly diagnosed thyroid dysfunction. Patients were evaluated clinically with hand held dynamometry and with electrodiagnosis. The clinical features of weakness and sensory signs and the biochemical data were evaluated during treatment. In hypothyroid patients 79% had neuromuscular complaints, 38% had clinical weakness (manual muscle strength testing) in one or more muscle groups, 42% had signs of sensorimotor axonal neuropathy, and 29% had carpal tunnel syndrome. Serum creatine kinase did not correlate with weakness. After 1 year of treatment 13% of the patients still had weakness. In hyperthyroid patients 67% had neuromuscular symptoms, 62% had clinical weakness in at least one muscle group that correlated with FT4 concentrations, but not with serum CK. Nineteen per cent of the patients had sensory-motor axonal neuropathy and 0% had carpal tunnel syndrome. The neuromuscular signs developed rapidly, early in the course of the disorder and were severe, but resolved rapidly and completely during treatment (average time 3.6 months). Neuromuscular symptoms and signs were present in most patients. About 40% of the hypothyroid patients and 20% of the hyperthyroid patients had predominantly sensory signs of a sensorimotor axonal neuropathy early in the course of thyroid disease. Weakness in hyperthyroidism evolved rapidly at an early stage of the disorder and resolved completely during treatment, suggesting a functional muscle disorder. Hand held dynamometry is sensitive for the detection of weakness and for the clinical evaluation of treatment effects. Weakness in hypothyroidism is more difficult to treat, suggesting myopathy.

Facial-muscle weakness, speech disorders and dysphagia are common in patients with classic infantile Pompe disease treated with enzyme therapy.

PubMed

van Gelder, C M; van Capelle, C I; Ebbink, B J; Moor-van Nugteren, I; van den Hout, J M P; Hakkesteegt, M M; van Doorn, P A; de Coo, I F M; Reuser, A J J; de Gier, H H W; van der Ploeg, A T

2012-05-01

Classic infantile Pompe disease is an inherited generalized glycogen storage disorder caused by deficiency of lysosomal acid α-glucosidase. If left untreated, patients die before one year of age. Although enzyme-replacement therapy (ERT) has significantly prolonged lifespan, it has also revealed new aspects of the disease. For up to 11 years, we investigated the frequency and consequences of facial-muscle weakness, speech disorders and dysphagia in long-term survivors. Sequential photographs were used to determine the timing and severity of facial-muscle weakness. Using standardized articulation tests and fibreoptic endoscopic evaluation of swallowing, we investigated speech and swallowing function in a subset of patients. This study included 11 patients with classic infantile Pompe disease. Median age at the start of ERT was 2.4 months (range 0.1-8.3 months), and median age at the end of the study was 4.3 years (range 7.7 months -12.2 years). All patients developed facial-muscle weakness before the age of 15 months. Speech was studied in four patients. Articulation was disordered, with hypernasal resonance and reduced speech intelligibility in all four. Swallowing function was studied in six patients, the most important findings being ineffective swallowing with residues of food (5/6), penetration or aspiration (3/6), and reduced pharyngeal and/or laryngeal sensibility (2/6). We conclude that facial-muscle weakness, speech disorders and dysphagia are common in long-term survivors receiving ERT for classic infantile Pompe disease. To improve speech and reduce the risk for aspiration, early treatment by a speech therapist and regular swallowing assessments are recommended.

Disordered artificial spin ices: Avalanches and criticality (invited)

NASA Astrophysics Data System (ADS)

Reichhardt, Cynthia J. Olson; Chern, Gia-Wei; Libál, Andras; Reichhardt, Charles

2015-05-01

We show that square and kagome artificial spin ices with disconnected islands exhibit disorder-induced nonequilibrium phase transitions. The critical point of the transition is characterized by a diverging length scale and the effective spin reconfiguration avalanche sizes are power-law distributed. For weak disorder, the magnetization reversal is dominated by system-spanning avalanche events characteristic of a supercritical regime, while at strong disorder, the avalanche distributions have subcritical behavior and are cut off above a length scale that decreases with increasing disorder. The different type of geometrical frustration in the two lattices produces distinct forms of critical avalanche behavior. Avalanches in the square ice consist of the propagation of locally stable domain walls separating the two polarized ground states, and we find a scaling collapse consistent with an interface depinning mechanism. In the fully frustrated kagome ice, however, the avalanches branch strongly in a manner reminiscent of directed percolation. We also observe an interesting crossover in the power-law scaling of the kagome ice avalanches at low disorder. Our results show that artificial spin ices are ideal systems in which to study a variety of nonequilibrium critical point phenomena as the microscopic degrees of freedom can be accessed directly in experiments.

Disordered artificial spin ices: Avalanches and criticality (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reichhardt, Cynthia J. Olson, E-mail: cjrx@lanl.gov; Chern, Gia-Wei; Reichhardt, Charles

2015-05-07

We show that square and kagome artificial spin ices with disconnected islands exhibit disorder-induced nonequilibrium phase transitions. The critical point of the transition is characterized by a diverging length scale and the effective spin reconfiguration avalanche sizes are power-law distributed. For weak disorder, the magnetization reversal is dominated by system-spanning avalanche events characteristic of a supercritical regime, while at strong disorder, the avalanche distributions have subcritical behavior and are cut off above a length scale that decreases with increasing disorder. The different type of geometrical frustration in the two lattices produces distinct forms of critical avalanche behavior. Avalanches in themore » square ice consist of the propagation of locally stable domain walls separating the two polarized ground states, and we find a scaling collapse consistent with an interface depinning mechanism. In the fully frustrated kagome ice, however, the avalanches branch strongly in a manner reminiscent of directed percolation. We also observe an interesting crossover in the power-law scaling of the kagome ice avalanches at low disorder. Our results show that artificial spin ices are ideal systems in which to study a variety of nonequilibrium critical point phenomena as the microscopic degrees of freedom can be accessed directly in experiments.« less

Interparticle interactions effects on the magnetic order in surface of FeO4 nanoparticles.

PubMed

Lima, E; Vargas, J M; Rechenberg, H R; Zysler, R D

2008-11-01

We report interparticle interactions effects on the magnetic structure of the surface region in Fe3O4 nanoparticles. For that, we have studied a desirable system composed by Fe3O4 nanoparticles with (d) = 9.3 nm and a narrow size distribution. These particles present an interesting morphology constituted by a crystalline core and a broad (approximately 50% vol.) disordered superficial shell. Two samples were prepared with distinct concentrations of the particles: weakly-interacting particles dispersed in a polymer and strongly-dipolar-interacting particles in a powder sample. M(H, T) measurements clearly show that strong dipolar interparticle interaction modifies the magnetic structure of the structurally disordered superficial shell. Consequently, we have observed drastically distinct thermal behaviours of magnetization and susceptibility comparing weakly- and strongly-interacting samples for the temperature range 2 K < T < 300 K. We have also observed a temperature-field dependence of the hysteresis loops of the dispersed sample that is not observed in the hysteresis loops of the powder one.

The weak coherence account: detail-focused cognitive style in autism spectrum disorders.

PubMed

Happé, Francesca; Frith, Uta

2006-01-01

"Weak central coherence" refers to the detail-focused processing style proposed to characterise autism spectrum disorders (ASD). The original suggestion of a core deficit in central processing resulting in failure to extract global form/meaning, has been challenged in three ways. First, it may represent an outcome of superiority in local processing. Second, it may be a processing bias, rather than deficit. Third, weak coherence may occur alongside, rather than explain, deficits in social cognition. A review of over 50 empirical studies of coherence suggests robust findings of local bias in ASD, with mixed findings regarding weak global processing. Local bias appears not to be a mere side-effect of executive dysfunction, and may be independent of theory of mind deficits. Possible computational and neural models are discussed.

Elephants in Pyjamas: Testing the Weak Central Coherence Account of Autism Spectrum Disorders Using a Syntactic Disambiguation Task.

PubMed

Riches, N G; Loucas, T; Baird, G; Charman, T; Simonoff, E

2016-01-01

According to the weak central coherence (CC) account individuals with autism spectrum disorders (ASD) exhibit enhanced local processing and weak part-whole integration. CC was investigated in the verbal domain. Adolescents, recruited using a 2 (ASD status) by 2 (language impairment status) design, completed an aural forced choice comprehension task involving syntactically ambiguous sentences. Half the picture targets depicted the least plausible interpretation, resulting in longer RTs across groups. These were assumed to reflect local processing. There was no ASD by plausibility interaction and consequently little evidence for weak CC in the verbal domain when conceptualised as enhanced local processing. Furthermore, there was little evidence that the processing of syntactically ambiguous sentences differed as a function of ASD or language-impairment status.

European guideline for the diagnosis and treatment of insomnia.

PubMed

Riemann, Dieter; Baglioni, Chiara; Bassetti, Claudio; Bjorvatn, Bjørn; Dolenc Groselj, Leja; Ellis, Jason G; Espie, Colin A; Garcia-Borreguero, Diego; Gjerstad, Michaela; Gonçalves, Marta; Hertenstein, Elisabeth; Jansson-Fröjmark, Markus; Jennum, Poul J; Leger, Damien; Nissen, Christoph; Parrino, Liborio; Paunio, Tiina; Pevernagie, Dirk; Verbraecken, Johan; Weeß, Hans-Günter; Wichniak, Adam; Zavalko, Irina; Arnardottir, Erna S; Deleanu, Oana-Claudia; Strazisar, Barbara; Zoetmulder, Marielle; Spiegelhalder, Kai

2017-12-01

This European guideline for the diagnosis and treatment of insomnia was developed by a task force of the European Sleep Research Society, with the aim of providing clinical recommendations for the management of adult patients with insomnia. The guideline is based on a systematic review of relevant meta-analyses published till June 2016. The target audience for this guideline includes all clinicians involved in the management of insomnia, and the target patient population includes adults with chronic insomnia disorder. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) system was used to grade the evidence and guide recommendations. The diagnostic procedure for insomnia, and its co-morbidities, should include a clinical interview consisting of a sleep history (sleep habits, sleep environment, work schedules, circadian factors), the use of sleep questionnaires and sleep diaries, questions about somatic and mental health, a physical examination and additional measures if indicated (i.e. blood tests, electrocardiogram, electroencephalogram; strong recommendation, moderate- to high-quality evidence). Polysomnography can be used to evaluate other sleep disorders if suspected (i.e. periodic limb movement disorder, sleep-related breathing disorders), in treatment-resistant insomnia, for professional at-risk populations and when substantial sleep state misperception is suspected (strong recommendation, high-quality evidence). Cognitive behavioural therapy for insomnia is recommended as the first-line treatment for chronic insomnia in adults of any age (strong recommendation, high-quality evidence). A pharmacological intervention can be offered if cognitive behavioural therapy for insomnia is not sufficiently effective or not available. Benzodiazepines, benzodiazepine receptor agonists and some antidepressants are effective in the short-term treatment of insomnia (≤4 weeks; weak recommendation, moderate-quality evidence). Antihistamines, antipsychotics, melatonin and phytotherapeutics are not recommended for insomnia treatment (strong to weak recommendations, low- to very-low-quality evidence). Light therapy and exercise need to be further evaluated to judge their usefulness in the treatment of insomnia (weak recommendation, low-quality evidence). Complementary and alternative treatments (e.g. homeopathy, acupuncture) are not recommended for insomnia treatment (weak recommendation, very-low-quality evidence). © 2017 European Sleep Research Society.

Motoneuron firing in amyotrophic lateral sclerosis (ALS)

PubMed Central

de Carvalho, Mamede; Eisen, Andrew; Krieger, Charles; Swash, Michael

2014-01-01

Amyotrophic lateral sclerosis is an inexorably progressive neurodegenerative disorder involving the classical motor system and the frontal effector brain, causing muscular weakness and atrophy, with variable upper motor neuron signs and often an associated fronto-temporal dementia. The physiological disturbance consequent on the motor system degeneration is beginning to be well understood. In this review we describe aspects of the motor cortical, neuronal, and lower motor neuron dysfunction. We show how studies of the changes in the pattern of motor unit firing help delineate the underlying pathophysiological disturbance as the disease progresses. Such studies are beginning to illuminate the underlying disordered pathophysiological processes in the disease, and are important in designing new approaches to therapy and especially for clinical trials. PMID:25294995

Wavepacket dynamics in one-dimensional system with long-range correlated disorder

NASA Astrophysics Data System (ADS)

Yamada, Hiroaki S.

2018-03-01

We numerically investigate dynamical property in the one-dimensional tight-binding model with long-range correlated disorder having power spectrum 1 /fα (α: spectrum exponent) generated by Fourier filtering method. For relatively small α <αc (=2) time-dependence of mean square displacement (MSD) of the initially localized wavepacket shows ballistic spread and localizes as time elapses. It is shown that α-dependence of the dynamical localization length determined by the MSD exhibits a simple scaling law in the localization regime for the relatively weak disorder strength W. Furthermore, scaled MSD by the dynamical localization length almost obeys an universal function from the ballistic to the localization regime in the various combinations of the parameters α and W.

The Comorbidity between Attention-Deficit/Hyperactivity Disorder (ADHD) in Children and Arabic Speech Sound Disorder

ERIC Educational Resources Information Center

Hariri, Ruaa Osama

2016-01-01

Children with Attention-Deficiency/Hyperactive Disorder (ADHD) often have co-existing learning disabilities and developmental weaknesses or delays in some areas including speech (Rief, 2005). Seeing that phonological disorders include articulation errors and other forms of speech disorders, studies pertaining to children with ADHD symptoms who…

Neuromuscular findings in thyroid dysfunction: a prospective clinical and electrodiagnostic study

PubMed Central

Duyff, R.; Van den Bosch, J.; Laman, D; van Loon, B.-J. P.; Linssen, W.

2000-01-01

OBJECTIVES—To evaluate neuromuscular signs and symptoms in patients with newly diagnosed hypothyroidism and hyperthyroidism.
METHODS—A prospective cohort study was performed in adult patients with newly diagnosed thyroid dysfunction. Patients were evaluated clinically with hand held dynamometry and with electrodiagnosis. The clinical features of weakness and sensory signs and the biochemical data were evaluated during treatment.
RESULTS—In hypothyroid patients 79% had neuromuscular complaints, 38% had clinical weakness (manual muscle strength testing) in one or more muscle groups, 42% had signs of sensorimotor axonal neuropathy, and 29% had carpal tunnel syndrome. Serum creatine kinase did not correlate with weakness. After 1 year of treatment 13% of the patients still had weakness. In hyperthyroid patients 67% had neuromuscular symptoms, 62% had clinical weakness in at least one muscle group that correlated with FT4 concentrations, but not with serum CK. Nineteen per cent of the patients had sensory-motor axonal neuropathy and 0% had carpal tunnel syndrome. The neuromuscular signs developed rapidly, early in the course of the disorder and were severe, but resolved rapidly and completely during treatment (average time 3.6months).
CONCLUSIONS—Neuromuscular symptoms and signs were present in most patients. About 40% of the hypothyroid patients and 20% of the hyperthyroid patients had predominantly sensory signs of a sensorimotor axonal neuropathy early in the course of thyroid disease. Weakness in hyperthyroidism evolved rapidly at an early stage of the disorder and resolved completely during treatment, suggesting a functional muscle disorder. Hand held dynamometry is sensitive for the detection of weakness and for the clinical evaluation of treatment effects. Weakness in hypothyroidism is more difficult to treat, suggesting myopathy.

 PMID:10811699

Rare-Region-Induced Avoided Quantum Criticality in Disordered Three-Dimensional Dirac and Weyl Semimetals

NASA Astrophysics Data System (ADS)

Pixley, J. H.; Huse, David A.; Das Sarma, S.

2016-04-01

We numerically study the effect of short-ranged potential disorder on massless noninteracting three-dimensional Dirac and Weyl fermions, with a focus on the question of the proposed (and extensively theoretically studied) quantum critical point separating semimetal and diffusive-metal phases. We determine the properties of the eigenstates of the disordered Dirac Hamiltonian (H ) and exactly calculate the density of states (DOS) near zero energy, using a combination of Lanczos on H2 and the kernel polynomial method on H . We establish the existence of two distinct types of low-energy eigenstates contributing to the disordered density of states in the weak-disorder semimetal regime. These are (i) typical eigenstates that are well described by linearly dispersing perturbatively dressed Dirac states and (ii) nonperturbative rare eigenstates that are weakly dispersive and quasilocalized in the real-space regions with the largest (and rarest) local random potential. Using twisted boundary conditions, we are able to systematically find and study these two (essentially independent) types of eigenstates. We find that the Dirac states contribute low-energy peaks in the finite-size DOS that arise from the clean eigenstates which shift and broaden in the presence of disorder. On the other hand, we establish that the rare quasilocalized eigenstates contribute a nonzero background DOS which is only weakly energy dependent near zero energy and is exponentially small at weak disorder. We also find that the expected semimetal to diffusive-metal quantum critical point is converted to an avoided quantum criticality that is "rounded out" by nonperturbative effects, with no signs of any singular behavior in the DOS at the energy of the clean Dirac point. However, the crossover effects of the avoided (or hidden) criticality manifest themselves in a so-called quantum critical fan region away from the Dirac energy. We discuss the implications of our results for disordered Dirac and Weyl semimetals, and reconcile the large body of existing numerical work showing quantum criticality with the existence of these nonperturbative effects.

Slow dynamics of electron glasses: The role of disorder

NASA Astrophysics Data System (ADS)

Ovadyahu, Z.

2017-04-01

We examine in this work the role of disorder in contributing to the sluggish relaxation observed in intrinsic electron glasses. Our approach is guided by several empirical observations: First and foremost, Anderson localization is a pre-requisite for observing these nonequilibrium phenomena. Secondly, sluggish relaxation appears to favor Anderson insulators with relatively large Fermi energies (hence proportionally large disorder). These observations motivated us to consider a way to measure the underlying disorder in a realistic Anderson insulator. Optical studies using a series of amorphous indium oxide (InxO ) establish a simple connection between carrier concentration and the disorder necessary to approach the metal-insulator transition from the insulating side. This is used to estimate the typical magnitude of the quenched potential fluctuation in the electron-glass phase of this system. The implications of our findings on the slow dynamics of Anderson insulators are discussed. In particular, the reason for the absence of a memory dip and the accompanying electron-glass effects in lightly-doped semiconductors emerges as a natural consequence of their weak disorder.

Disorder effects in topological states: Brief review of the recent developments

NASA Astrophysics Data System (ADS)

Wu, Binglan; Song, Juntao; Zhou, Jiaojiao; Jiang, Hua

2016-11-01

Disorder inevitably exists in realistic samples, manifesting itself in various exotic properties for the topological states. In this paper, we summarize and briefly review the work completed over the last few years, including our own, regarding recent developments in several topics about disorder effects in topological states. For weak disorder, the robustness of topological states is demonstrated, especially for both quantum spin Hall states with Z 2 = 1 and size induced nontrivial topological insulators with Z 2 = 0. For moderate disorder, by increasing the randomness of both the impurity distribution and the impurity induced potential, the topological insulator states can be created from normal metallic or insulating states. These phenomena and their mechanisms are summarized. For strong disorder, the disorder causes a metal-insulator transition. Due to their topological nature, the phase diagrams are much richer in topological state systems. Finally, the trends in these areas of disorder research are discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374219, 11474085, and 11534001) and the Natural Science Foundation of Jiangsu Province, China (Grant No BK20160007).

Annual Research Review: The nature and classification of reading disorders – a commentary on proposals for DSM-5

PubMed Central

Snowling, Margaret J; Hulme, Charles

2012-01-01

This article reviews our understanding of reading disorders in children and relates it to current proposals for their classification in DSM-5. There are two different, commonly occurring, forms of reading disorder in children which arise from different underlying language difficulties. Dyslexia (as defined in DSM-5), or decoding difficulty, refers to children who have difficulty in mastering the relationships between the spelling patterns of words and their pronunciations. These children typically read aloud inaccurately and slowly, and experience additional problems with spelling. Dyslexia appears to arise principally from a weakness in phonological (speech sound) skills, and there is good evidence that it can be ameliorated by systematic phonic teaching combined with phonological awareness training. The other major form of reading difficulty is reading comprehension impairment. These children read aloud accurately and fluently, but have difficulty understanding what they have read. Reading comprehension impairment appears to arise from weaknesses in a range of oral language skills including poor vocabulary knowledge, weak grammatical skills and difficulties in oral language comprehension. We suggest that the omission of reading comprehension impairment from DSM-5 is a serious one that should be remedied. Both dyslexia and reading comprehension impairment are dimensional in nature, and show strong continuities with other disorders of language. We argue that recognizing the continuities between reading and language disorders has important implications for assessment and treatment, and we note that the high rates of comorbidity between reading disorders and other seemingly disparate disorders (including ADHD and motor disorders) raises important challenges for understanding these disorders. PMID:22141434

From inverse problems to learning: a Statistical Mechanics approach

NASA Astrophysics Data System (ADS)

Baldassi, Carlo; Gerace, Federica; Saglietti, Luca; Zecchina, Riccardo

2018-01-01

We present a brief introduction to the statistical mechanics approaches for the study of inverse problems in data science. We then provide concrete new results on inferring couplings from sampled configurations in systems characterized by an extensive number of stable attractors in the low temperature regime. We also show how these result are connected to the problem of learning with realistic weak signals in computational neuroscience. Our techniques and algorithms rely on advanced mean-field methods developed in the context of disordered systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanz, Alejandro; Ezquerra, Tiberio A.; Nogales, Aurora, E-mail: aurora.nogales@csic.es

The dynamics of lower disorder-order temperature diblock copolymer leading to phase separation has been observed by X ray photon correlation spectroscopy. Two different modes have been characterized. A non-diffusive mode appears at temperatures below the disorder to order transition, which can be associated to compositional fluctuations, that becomes slower as the interaction parameter increases, in a similar way to the one observed for diblock copolymers exhibiting phase separation upon cooling. At temperatures above the disorder to order transition T{sub ODT}, the dynamics becomes diffusive, indicating that after phase separation in Lower Disorder-Order Transition (LDOT) diblock copolymers, the diffusion of chainmore » segments across the interface is the governing dynamics. As the segregation is stronger, the diffusive process becomes slower. Both observed modes have been predicted by the theory describing upper order-disorder transition systems, assuming incompressibility. However, the present results indicate that the existence of these two modes is more universal as they are present also in compressible diblock copolymers exhibiting a lower disorder-order transition. No such a theory describing the dynamics in LDOT block copolymers is available, and these experimental results may offer some hints to understanding the dynamics in these systems. The dynamics has also been studied in the ordered state, and for the present system, the non-diffusive mode disappears and only a diffusive mode is observed. This mode is related to the transport of segment in the interphase, due to the weak segregation on this system.« less

Practical Recommendations for Diagnosis and Management of Respiratory Muscle Weakness in Late-Onset Pompe Disease

PubMed Central

Boentert, Matthias; Prigent, Hélène; Várdi, Katalin; Jones, Harrison N.; Mellies, Uwe; Simonds, Anita K.; Wenninger, Stephan; Barrot Cortés, Emilia; Confalonieri, Marco

2016-01-01

Pompe disease is an autosomal-recessive lysosomal storage disorder characterized by progressive myopathy with proximal muscle weakness, respiratory muscle dysfunction, and cardiomyopathy (in infants only). In patients with juvenile or adult disease onset, respiratory muscle weakness may decline more rapidly than overall neurological disability. Sleep-disordered breathing, daytime hypercapnia, and the need for nocturnal ventilation eventually evolve in most patients. Additionally, respiratory muscle weakness leads to decreased cough and impaired airway clearance, increasing the risk of acute respiratory illness. Progressive respiratory muscle weakness is a major cause of morbidity and mortality in late-onset Pompe disease even if enzyme replacement therapy has been established. Practical knowledge of how to detect, monitor and manage respiratory muscle involvement is crucial for optimal patient care. A multidisciplinary approach combining the expertise of neurologists, pulmonologists, and intensive care specialists is needed. Based on the authors’ own experience in over 200 patients, this article conveys expert recommendations for the diagnosis and management of respiratory muscle weakness and its sequelae in late-onset Pompe disease. PMID:27763517

Emulating weak localization using a solid-state quantum circuit.

PubMed

Chen, Yu; Roushan, P; Sank, D; Neill, C; Lucero, Erik; Mariantoni, Matteo; Barends, R; Chiaro, B; Kelly, J; Megrant, A; Mutus, J Y; O'Malley, P J J; Vainsencher, A; Wenner, J; White, T C; Yin, Yi; Cleland, A N; Martinis, John M

2014-10-14

Quantum interference is one of the most fundamental physical effects found in nature. Recent advances in quantum computing now employ interference as a fundamental resource for computation and control. Quantum interference also lies at the heart of sophisticated condensed matter phenomena such as Anderson localization, phenomena that are difficult to reproduce in numerical simulations. Here, employing a multiple-element superconducting quantum circuit, with which we manipulate a single microwave photon, we demonstrate that we can emulate the basic effects of weak localization. By engineering the control sequence, we are able to reproduce the well-known negative magnetoresistance of weak localization as well as its temperature dependence. Furthermore, we can use our circuit to continuously tune the level of disorder, a parameter that is not readily accessible in mesoscopic systems. Demonstrating a high level of control, our experiment shows the potential for employing superconducting quantum circuits as emulators for complex quantum phenomena.

Is bruxism a disorder or a behaviour? Rethinking the international consensus on defining and grading of bruxism.

PubMed

Raphael, K G; Santiago, V; Lobbezoo, F

2016-10-01

Inspired by the international consensus on defining and grading of bruxism (Lobbezoo F, Ahlberg J, Glaros AG, Kato T, Koyano K, Lavigne GJ et al. J Oral Rehabil. 2013;40:2), this commentary examines its contribution and underlying assumptions for defining sleep bruxism (SB). The consensus' parsimonious redefinition of bruxism as a behaviour is an advance, but we explore an implied question: might SB be more than behaviour? Behaviours do not inherently require clinical treatment, making the consensus-proposed 'diagnostic grading system' inappropriate. However, diagnostic grading might be useful, if SB were considered a disorder. Therefore, to fully appreciate the contribution of the consensus statement, we first consider standards and evidence for determining whether SB is a disorder characterised by harmful dysfunction or a risk factor increasing probability of a disorder. Second, the strengths and weaknesses of the consensus statement's proposed 'diagnostic grading system' are examined. The strongest evidence-to-date does not support SB as disorder as implied by 'diagnosis'. Behaviour alone is not diagnosed; disorders are. Considered even as a grading system of behaviour, the proposed system is weakened by poor sensitivity of self-report for direct polysomnographic (PSG)-classified SB and poor associations between clinical judgments of SB and portable PSG; reliance on dichotomised reports; and failure to consider SB behaviour on a continuum, measurable and definable through valid behavioural observation. To date, evidence for validity of self-report or clinician report in placing SB behaviour on a continuum is lacking, raising concerns about their potential utility in any bruxism behavioural grading system, and handicapping future study of whether SB may be a useful risk factor for, or itself a disorder requiring treatment. © 2016 John Wiley & Sons Ltd.

Universality from disorder in the random-bond Blume-Capel model

NASA Astrophysics Data System (ADS)

Fytas, N. G.; Zierenberg, J.; Theodorakis, P. E.; Weigel, M.; Janke, W.; Malakis, A.

2018-04-01

Using high-precision Monte Carlo simulations and finite-size scaling we study the effect of quenched disorder in the exchange couplings on the Blume-Capel model on the square lattice. The first-order transition for large crystal-field coupling is softened to become continuous, with a divergent correlation length. An analysis of the scaling of the correlation length as well as the susceptibility and specific heat reveals that it belongs to the universality class of the Ising model with additional logarithmic corrections which is also observed for the Ising model itself if coupled to weak disorder. While the leading scaling behavior of the disordered system is therefore identical between the second-order and first-order segments of the phase diagram of the pure model, the finite-size scaling in the ex-first-order regime is affected by strong transient effects with a crossover length scale L*≈32 for the chosen parameters.

Neuropsychological Functioning in Childhood-Onset Psychosis and Attention-Deficit/Hyperactivity Disorder

ERIC Educational Resources Information Center

Brodsky, Kimberly; Willcutt, Erik G.; Davalos, Deana B.; Ross, Randal G.

2014-01-01

Background: Attention-deficit/hyperactivity disorder (ADHD) and childhood-onset psychosis (COP) are chronic, heterogeneous disorders with symptoms that frequently co-occur, but the etiology of their comorbidity is unknown. Studies of each disorder indicate that both ADHD and COP are associated with a range of neuropsychological weaknesses, but few…

Finite-temperature fluid–insulator transition of strongly interacting 1D disordered bosons

PubMed Central

Michal, Vincent P.; Aleiner, Igor L.; Altshuler, Boris L.; Shlyapnikov, Georgy V.

2016-01-01

We consider the many-body localization–delocalization transition for strongly interacting one-dimensional disordered bosons and construct the full picture of finite temperature behavior of this system. This picture shows two insulator–fluid transitions at any finite temperature when varying the interaction strength. At weak interactions, an increase in the interaction strength leads to insulator → fluid transition, and, for large interactions, there is a reentrance to the insulator regime. It is feasible to experimentally verify these predictions by tuning the interaction strength with the use of Feshbach or confinement-induced resonances, for example, in 7Li or 39K. PMID:27436894

Annual research review: the nature and classification of reading disorders--a commentary on proposals for DSM-5.

PubMed

Snowling, Margaret J; Hulme, Charles

2012-05-01

This article reviews our understanding of reading disorders in children and relates it to current proposals for their classification in DSM-5. There are two different, commonly occurring, forms of reading disorder in children which arise from different underlying language difficulties. Dyslexia (as defined in DSM-5), or decoding difficulty, refers to children who have difficulty in mastering the relationships between the spelling patterns of words and their pronunciations. These children typically read aloud inaccurately and slowly, and experience additional problems with spelling. Dyslexia appears to arise principally from a weakness in phonological (speech sound) skills, and there is good evidence that it can be ameliorated by systematic phonic teaching combined with phonological awareness training. The other major form of reading difficulty is reading comprehension impairment. These children read aloud accurately and fluently, but have difficulty understanding what they have read. Reading comprehension impairment appears to arise from weaknesses in a range of oral language skills including poor vocabulary knowledge, weak grammatical skills and difficulties in oral language comprehension. We suggest that the omission of reading comprehension impairment from DSM-5 is a serious one that should be remedied. Both dyslexia and reading comprehension impairment are dimensional in nature, and show strong continuities with other disorders of language. We argue that recognizing the continuities between reading and language disorders has important implications for assessment and treatment, and we note that the high rates of comorbidity between reading disorders and other seemingly disparate disorders (including ADHD and motor disorders) raises important challenges for understanding these disorders. © 2011 The Authors. Journal of Child Psychology and Psychiatry © 2011 Association for Child and Adolescent Mental Health.

Neuropsychological investigations in obsessive-compulsive disorder: A systematic review of methodological challenges.

PubMed

Abramovitch, Amitai; Mittelman, Andrew; Tankersley, Amelia P; Abramowitz, Jonathan S; Schweiger, Avraham

2015-07-30

The inconsistent nature of the neuropsychology literature pertaining to obsessive-compulsive disorder (OCD) has long been recognized. However, individual studies, systematic reviews, and recent meta-analytic reviews were unsuccessful in establishing a consensus regarding a disorder-specific neuropsychological profile. In an attempt to identify methodological factors that may contribute to the inconsistency that is characteristic of this body of research, a systematic review of methodological factors in studies comparing OCD patients and non-psychiatric controls on neuropsychological tests was conducted. This review covered 115 studies that included nearly 3500 patients. Results revealed a range of methodological weaknesses. Some of these weaknesses have been previously noted in the broader neuropsychological literature, while some are more specific to psychiatric disorders, and to OCD. These methodological shortcomings have the potential to hinder the identification of a specific neuropsychological profile associated with OCD as well as to obscure the association between neurocognitive dysfunctions and contemporary neurobiological models. Rectifying these weaknesses may facilitate replicability, and promote our ability to extract cogent, meaningful, and more unified inferences regarding the neuropsychology of OCD. To that end, we present a set of methodological recommendations to facilitate future neuropsychology research in psychiatric disorders in general, and in OCD in particular. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Correlation study of real delay time and imaginary delay time in 1-dimensional weak disorder optical media

NASA Astrophysics Data System (ADS)

Sahay, Peeyush; Almabadi, Huda M.; Pradhan, Prabhakar

Real delay time (τr) provides a measure of the time spent by photons inside an optical system. The measurement of τr is conducted in terms of energy (E) derivative of the Wigner phase delay (φ) , as τr = dϕ / dE dϕ / cdk k and c represents wavenumber and the speed of light, respectively. The characterization of τr requires interferometric system to measure φ of the light waves scattering from the medium [ R =√{ r} exp (- iϕ) ]. We investigated the possibility of extracting the τr information from the intensity measurement of the backscattered waves. The study was performed on a 1D model of weak disordered optical system and short sample length by numerically evaluating the backscattered light intensity. An imaginary delay time (τi) , defined as τi = dθ / cdk , where θ represents an `imaginary phase', was obtained upon expressing the backscattered intensity as RR* =| R | 2 = r = exp (- θ) . The result shows a strong correlation between r and φ with τr and τi exhibiting similar statistical distribution but with a shift. The magnitude and variation of the mean and std values of τr, and the std values of τi with sample lengths are nearly the same, which indicates about one parameter theory of delay time. This work potentially paves way for extracting phase information from the intensity distribution without using interferometric systems.

Sampling Long- versus Short-Range Interactions Defines the Ability of Force Fields To Reproduce the Dynamics of Intrinsically Disordered Proteins.

PubMed

Mercadante, Davide; Wagner, Johannes A; Aramburu, Iker V; Lemke, Edward A; Gräter, Frauke

2017-09-12

Molecular dynamics (MD) simulations have valuably complemented experiments describing the dynamics of intrinsically disordered proteins (IDPs), particularly since the proposal of models to solve the artificial collapse of IDPs in silico. Such models suggest redefining nonbonded interactions, by either increasing water dispersion forces or adopting the Kirkwood-Buff force field. These approaches yield extended conformers that better comply with experiments, but it is unclear if they all sample the same intrachain dynamics of IDPs. We have tested this by employing MD simulations and single-molecule Förster resonance energy transfer spectroscopy to sample the dimensions of systems with different sequence compositions, namely strong and weak polyelectrolytes. For strong polyelectrolytes in which charge effects dominate, all the proposed solutions equally reproduce the expected ensemble's dimensions. For weak polyelectrolytes, at lower cutoffs, force fields abnormally alter intrachain dynamics, overestimating excluded volume over chain flexibility or reporting no difference between the dynamics of different chains. The TIP4PD water model alone can reproduce experimentally observed changes in extensions (dimensions), but not quantitatively and with only weak statistical significance. Force field limitations are reversed with increased interaction cutoffs, showing that chain dynamics are critically defined by the presence of long-range interactions. Force field analysis aside, our study provides the first insights into how long-range interactions critically define IDP dimensions and raises the question of which length range is crucial to correctly sample the overall dimensions and internal dynamics of the large group of weakly charged yet highly polar IDPs.

Incidence and 12-month outcome of non-transient childhood conversion disorder in the U.K. and Ireland.

PubMed

Ani, Cornelius; Reading, Richard; Lynn, Richard; Forlee, Simone; Garralda, Elena

2013-06-01

Little is known about conversion disorder in childhood. To document clinical incidence, features, management and 12-month outcome of non-transient conversion disorder in under 16-year-olds in the U.K. and Ireland. Surveillance through the British Paediatric Surveillance Unit and Child and Adolescent Psychiatry Surveillance System. In total, 204 cases (age range 7-15 years) were reported, giving a 12-month incidence of 1.30/100 000 (95% CI 1.11-1.52). The most common symptoms were motor weakness and abnormal movements. Presentation with multiple symptoms was the norm. Antecedent stressors were reported for 80.8%, most commonly bullying in school. Most children required in-patient admission with frequent medical investigations. Follow-up at 12 months was available for 147 children, when all conversion disorder symptoms were reported as improved. Most families (91%) accepted a non-medical explanation of the symptoms either fully or partially. Childhood conversion disorder represents an infrequent but significant clinical burden in the UK and Ireland.

Shock Effect or Ships Passing in the Night: The Role of Armored Forces in Fourth Generation Warfare

DTIC Science & Technology

2003-06-23

effects- based planning, by immediately making clear the limitations and constraints of the use of such force. It is certain that as an instrument of the...advantage of the weaknesses of disorder; conversely, disorder takes advantage of the weaknesses of order. Based upon the strategic aims of the...generations of war with their overlapping political, economic, social , military, and mass media arenas makes determining the type of war we are entering more

Comorbidities in Preschool Children at Family Risk of Dyslexia

ERIC Educational Resources Information Center

Gooch, Debbie; Hulme, Charles; Nash, Hannah M.; Snowling, Margaret J.

2014-01-01

Background: Comorbidity among developmental disorders such as dyslexia, language impairment, attention deficit/hyperactivity disorder and developmental coordination disorder is common. This study explores comorbid weaknesses in preschool children at family risk of dyslexia with and without language impairment and considers the role that…

Role of analgesics, sedatives, neuromuscular blockers, and delirium.

PubMed

Hall, Jesse B; Schweickert, William; Kress, John P

2009-10-01

A major focus on critical care medicine concerns the institution of life-support therapies, such as mechanical ventilation, during periods of organ failure to permit a window of opportunity to diagnose and treat underlying disorders so that patients may be returned to their prior functional status upon recovery. With the growing success of these intensive care unit-based therapies and longer-term follow-up of patients, severe weakness involving the peripheral nervous system and muscles has been identified in many recovering patients, often confounding the time course or magnitude of recovery. Mechanical ventilation is often accompanied by pharmacologic treatments including analgesics, sedatives, and neuromuscular blockers. These drugs and the encephalopathies accompanying some forms of critical illness result in a high prevalence of delirium in mechanically ventilated patients. These drug effects likely contribute to an impaired ability to assess the magnitude of intensive care unit-acquired weakness, to additional time spent immobilized and mechanically ventilated, and to additional weakness from the patient's relative immobility and bedridden state. This review surveys recent literature documenting these relationships and identifying approaches to minimize pharmacologic contributions to intensive care unit-acquired weakness.

Colossal magnetoresistance in amino-functionalized graphene quantum dots at room temperature: manifestation of weak anti-localization and doorway to spintronics

NASA Astrophysics Data System (ADS)

Roy, Rajarshi; Thapa, Ranjit; Kumar, Gundam Sandeep; Mazumder, Nilesh; Sen, Dipayan; Sinthika, S.; Das, Nirmalya S.; Chattopadhyay, Kalyan K.

2016-04-01

In this work, we have demonstrated the signatures of localized surface distortions and disorders in functionalized graphene quantum dots (fGQD) and consequences in magneto-transport under weak field regime (~1 Tesla) at room temperature. Observed positive colossal magnetoresistance (MR) and its suppression is primarily explained by weak anti-localization phenomenon where competitive valley (inter and intra) dependent scattering takes place at room temperature under low magnetic field; analogous to low mobility disordered graphene samples. Furthermore, using ab-initio analysis we show that sub-lattice sensitive spin-polarized ground state exists in the GQD as a result of pz orbital asymmetry in GQD carbon atoms with amino functional groups. This spin polarized ground state is believed to help the weak anti-localization dependent magneto transport by generating more disorder and strain in a GQD lattice under applied magnetic field and lays the premise for future graphene quantum dot based spintronic applications.In this work, we have demonstrated the signatures of localized surface distortions and disorders in functionalized graphene quantum dots (fGQD) and consequences in magneto-transport under weak field regime (~1 Tesla) at room temperature. Observed positive colossal magnetoresistance (MR) and its suppression is primarily explained by weak anti-localization phenomenon where competitive valley (inter and intra) dependent scattering takes place at room temperature under low magnetic field; analogous to low mobility disordered graphene samples. Furthermore, using ab-initio analysis we show that sub-lattice sensitive spin-polarized ground state exists in the GQD as a result of pz orbital asymmetry in GQD carbon atoms with amino functional groups. This spin polarized ground state is believed to help the weak anti-localization dependent magneto transport by generating more disorder and strain in a GQD lattice under applied magnetic field and lays the premise for future graphene quantum dot based spintronic applications. Electronic supplementary information (ESI) available: UV-Vis spectrum of synthesized fGQDs, reconstructed false color surface topographic images from a high-resolution fGQD TEM lattice; Raman spectra with corresponding Breit-Wigner-Fano (BWF) line fitting of `G band' before and after the application of sTMF, spin density distribution (SDD) with different shapes of a functionalized graphene quantum dot, SDD of the main simulated fGQD model obtained using different exchange correlation functional (PW91, RBPE and LDA). Models of (a) two NH2 molecules adsorbed on a graphene sheet (periodic structure), (b) representing corresponding SPDOS are also provided. Charge density distribution (CDD) with two-dimensional side view contour plots of adsorbed -NH2 and O&z.dbd;C-NH2 on GQD lattice and SPDOS of a main fGQD model with 0.2% strain. See DOI: 10.1039/c5nr09292b

Fatigue of muscles weakened by death of motoneurons.

PubMed

Thomas, Christine K; Zijdewind, Inge

2006-01-01

Weakness is a characteristic of muscles influenced by the postpolio syndrome (PPS), amyotrophic lateral sclerosis (ALS), and spinal cord injury (SCI). The strength deficits relate to changes in muscle use and to the chronic denervation that can follow the spinal motoneuron death common to these disorders. PPS, ALS, and SCI also involve variable amounts of supraspinal neuron death, the effects of which on muscle weakness remains unclear. Nevertheless, weakness of muscle itself defines the functional consequences of these disorders. A weaker muscle requires an individual to work that muscle at higher than usual intensities relative to its maximal capacity, inducing progressive fatigue and an increased sense of effort. Little evidence is available to suggest that the fatigue commonly experienced by individuals with these disorders relates to an increase in the intrinsic fatigability of the muscle fibers. The only exception is when SCI induces chronic muscle paralysis. To reduce long-term functional deficits in these disorders, studies must identify the signaling pathways that influence neuron survival and determine the factors that encourage and limit sprouting of motor axons. This may ensure that a greater proportion of the fibers in each muscle remain innervated and available for use.

Non-equlibrium relaxation of vortex lines in disordered type-II superconductors

NASA Astrophysics Data System (ADS)

Dobramysl, Ulrich; Assi, Hiba; Pleimling, Michel; T&äUber, Uwe C.

2013-03-01

Vortex matter in disordered type-II superconductors display a remarkable wealth of behavior, ranging from hexagonally arranged crystals and a vortex liquid to glassy phases. The type and strength of the disorder has a profound influence on the structural properties of the vortex matter: Randomly distributed weak point pinning sites lead to the destruction of long range order and a Bragg glass phase; correlated, columnar disorder can yield a Bose glass phase with infinite tilt modulus. We employ a three-dimensional elastic line model and apply a Langevin molecular dynamics algorithm to simulate the dynamics of vortex lines in a dissipative medium. We investigate the relaxation of a system of lines that were initially prepared in an out-of-equilibrium state and characterize the transient behavior via two-time quantities. We vary the disorder type and strength and compare our results for random and columnar disorder. Research supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-09ER46613.

Discovery of Small Molecules that Inhibit the Disordered Protein, p27Kip1

PubMed Central

Iconaru, Luigi I.; Ban, David; Bharatham, Kavitha; Ramanathan, Arvind; Zhang, Weixing; Shelat, Anang A.; Zuo, Jian; Kriwacki, Richard W.

2015-01-01

Disordered proteins are highly prevalent in biological systems, they control myriad signaling and regulatory processes, and their levels and/or cellular localization are often altered in human disease. In contrast to folded proteins, disordered proteins, due to conformational heterogeneity and dynamics, are not considered viable drug targets. We challenged this paradigm by identifying through NMR-based screening small molecules that bound specifically, albeit weakly, to the disordered cell cycle regulator, p27Kip1 (p27). Two groups of molecules bound to sites created by transient clusters of aromatic residues within p27. Conserved chemical features within these two groups of small molecules exhibited complementarity to their binding sites within p27, establishing structure-activity relationships for small molecule:disordered protein interactions. Finally, one compound counteracted the Cdk2/cyclin A inhibitory function of p27 in vitro, providing proof-of-principle that small molecules can inhibit the function of a disordered protein (p27) through sequestration in a conformation incapable of folding and binding to a natural regulatory target (Cdk2/cyclin A). PMID:26507530

Discovery of Small Molecules that Inhibit the Disordered Protein, p27 Kip1

DOE PAGES

Iconaru, Luigi I.; Ban, David; Bharatham, Kavitha; ...

2015-10-28

In disordered proteins we see that they are highly prevalent in biological systems. They control myriad signaling and regulatory processes, and their levels and/or cellular localization are often altered in human disease. In contrast to folded proteins, disordered proteins, due to conformational heterogeneity and dynamics, are not considered viable drug targets. We challenged this paradigm by identifying through NMR-based screening small molecules that bound specifically, albeit weakly, to the disordered cell cycle regulator, p27 Kip1 (p27). Moreover, two groups of molecules bound to sites created by transient clusters of aromatic residues within p27. Conserved chemical features within these two groupsmore » of small molecules exhibited complementarity to their binding sites within p27, establishing structure-activity relationships for small molecule: disordered protein interactions. Finally, one compound counteracted the Cdk2/cyclin A inhibitory function of p27 in vitro, providing proof-of- principle that small molecules can inhibit the function of a disordered protein (p27) through sequestration in a conformation incapable of folding and binding to a natural regulatory target (Cdk2/cyclin A).« less

Power generation in random diode arrays

NASA Astrophysics Data System (ADS)

Shvydka, Diana; Karpov, V. G.

2005-03-01

We discuss nonlinear disordered systems, random diode arrays (RDAs), which can represent such objects as large-area photovoltaics and ion channels of biological membranes. Our numerical modeling has revealed several interesting properties of RDAs. In particular, the geometrical distribution of nonuniformities across a RDA has only a minor effect on its integral characteristics determined by RDA parameter statistics. In the meantime, the dispersion of integral characteristics vs system size exhibits a nontrivial scaling dependence. Our theoretical interpretation here remains limited and is based on the picture of eddy currents flowing through weak diodes in the RDA.

Interfacial adsorption in two-dimensional pure and random-bond Potts models.

PubMed

Fytas, Nikolaos G; Theodorakis, Panagiotis E; Malakis, Anastasios

2017-03-01

We use Monte Carlo simulations to study the finite-size scaling behavior of the interfacial adsorption of the two-dimensional square-lattice q-states Potts model. We consider the pure and random-bond versions of the Potts model for q=3,4,5,8, and 10, thus probing the interfacial properties at the originally continuous, weak, and strong first-order phase transitions. For the pure systems our results support the early scaling predictions for the size dependence of the interfacial adsorption at both first- and second-order phase transitions. For the disordered systems, the interfacial adsorption at the (disordered induced) continuous transitions is discussed, applying standard scaling arguments and invoking findings for bulk critical properties. The self-averaging properties of the interfacial adsorption are also analyzed by studying the infinite limit-size extrapolation of properly defined signal-to-noise ratios.

Room-Temperature Micron-Scale Exciton Migration in a Stabilized Emissive Molecular Aggregate.

PubMed

Caram, Justin R; Doria, Sandra; Eisele, Dörthe M; Freyria, Francesca S; Sinclair, Timothy S; Rebentrost, Patrick; Lloyd, Seth; Bawendi, Moungi G

2016-11-09

We report 1.6 ± 1 μm exciton transport in self-assembled supramolecular light-harvesting nanotubes (LHNs) assembled from amphiphillic cyanine dyes. We stabilize LHNs in a sucrose glass matrix, greatly reducing light and oxidative damage and allowing the observation of exciton-exciton annihilation signatures under weak excitation flux. Fitting to a one-dimensional diffusion model, we find an average exciton diffusion constant of 55 ± 20 cm 2 /s, among the highest measured for an organic system. We develop a simple model that uses cryogenic measurements of static and dynamic energetic disorder to estimate a diffusion constant of 32 cm 2 /s, in agreement with experiment. We ascribe large exciton diffusion lengths to low static and dynamic energetic disorder in LHNs. We argue that matrix-stabilized LHNS represent an excellent model system to study coherent excitonic transport.

Alterations in tendon microenvironment in response to mechanical load: potential molecular targets for treatment strategies

PubMed Central

Fouda, Mohamed B; Thankam, Finosh G; Dilisio, Matthew F; Agrawal, Devendra K

2017-01-01

Rotator cuff (RC) tendons could beinflicted in many ways with an eventual outcome of pain, weakness and disability, which represent a large burden on health care cost. However, optimal healing, either conservatively or with surgical intervention, remains an issue that needs further investigation. Disorders of the RC tendons may result from external factors like trauma, or internal factors through physiologic and metabolic derangement. Most RC tendon disorders may be asymptomatic and may result from an over-activity of the inflicted shoulder and its tendons. Such tendon disorders are poorly diagnosed since patients do not seek medical attention until pain or weakness ensue. Immunological and biochemical events in RC disorders due to mechanical intolerance have not been investigated. Generally, the mechanical load drives normal physiological properties of the tendon. But, mechanical overload/burden exerts stress on tenocytes, and disrupts the tendon microenvironment by triggering a multitude of signaling pathways leading to extracellular matrix remodeling, disorganization, alteration in collagen composition and apoptosis. These events result in weak tendon which is highly susceptible to rupture or tear. In this article, we critically reviewed the intrinsic signaling pathways that are excessively triggered by continuous mechanical load and the counteracting physiological responses and associated derangements. The elucidation of the molecular events underlying mechanical stress-induced symptomatic/asymptomatic tendinopathy could provide information on potential target sites for translational application in the management of rotator cuff disorders. PMID:29118899

Phenomenology of panic attacks: a descriptive study of panic disorder patients' self-reports.

PubMed

Aronson, T A; Logue, C M

1988-01-01

The phenomenology of panic disorder and panic attacks was systematically assessed in 46 consecutive patients. The results suggest that DSM-III criteria include several symptoms that are not frequently present during a panic attack and that DSM-III's characterization of a panic attack is imprecise and misleading. Panic attacks were found to vary in intensity, frequency, spontaneity, and associated symptoms. A panic attack typically presents as a unified symptom complex of psychic anxiety and multiple somatic symptoms in multiple body systems. It occurs in a crescendolike pattern, is self-limited, and often leaves the subject weak or shaken. The temporal course as much as the symptomatic presentation defines a panic attack.

The Khmer ‘Weak Heart’ Syndrome: Fear of Death from Palpitations

PubMed Central

Hinton, Devon; Hinton, Susan; Um, Khin; Chea, Audria; Sak, Sophia

2009-01-01

According to the Khmer conception, a person suffering ‘weak heart’ (khsaoy beh daung) has episodes of palpitations on slight provocation (e.g. triggered by orthostasis, anger, a noise, worry, an odor or exercise) and runs the risk of dying of heart arrest during these periods of palpitations; too, the sufferer typically has other symptoms attributed to the purported cardiac dysfunction: fatigue, shortness of breath, and orthostatic dizziness. Many Khmer refugees suffer this cultural syndrome, an anxious–dysphoria ontology, most probably of French colonial provenance. The syndrome demonstrates considerable overlap with those Western illness categories that feature panic attacks, in particular post-traumatic stress disorder (PTSD) and panic disorder. In a psychiatric clinic survey, 60 percent (60/100) of those assessed believed themselves to currently suffer ‘weak heart’; 90 percent (54/60) of those considering themselves to suffer from ‘weak heart’ thought that palpitations (e.g., those resulting from a loud noise or orthostasis) might result in death. The article illustrates the profoundly culturally constructed nature of ‘cardiac sensations,’ located in a specific historical trajectory and episteme; too, the article suggests that trauma may result more in panic disorder than ‘PTSD’ when autonomic arousal symptoms (in the present case, palpitations) are considered potentially life-threatening. PMID:20814562

Phonons in random alloys: The itinerant coherent-potential approximation

NASA Astrophysics Data System (ADS)

Ghosh, Subhradip; Leath, P. L.; Cohen, Morrel H.

2002-12-01

We present the itinerant coherent-potential approximation (ICPA), an analytic, translationally invariant, and tractable form of augmented-space-based multiple-scattering theory18 in a single-site approximation for harmonic phonons in realistic random binary alloys with mass and force-constant disorder. We provide expressions for quantities needed for comparison with experimental structure factors such as partial and average spectral functions and derive the sum rules associated with them. Numerical results are presented for Ni55Pd45 and Ni50Pt50 alloys which serve as test cases, the former for weak force-constant disorder and the latter for strong. We present results on dispersion curves and disorder-induced widths. Direct comparisons with the single-site coherent potential approximation (CPA) and experiment are made which provide insight into the physics of force-constant changes in random alloys. The CPA accounts well for the weak force-constant disorder case but fails for strong force-constant disorder where the ICPA succeeds.

Disease-Induced Skeletal Muscle Atrophy and Fatigue

PubMed Central

Powers, Scott K.; Lynch, Gordon S.; Murphy, Kate T.; Reid, Michael B.; Zijdewind, Inge

2016-01-01

Numerous health problems including acute critical illness, cancer, diseases associated with chronic inflammation, and neurological disorders often result in skeletal muscle weakness and fatigue. Disease-related muscle atrophy and fatigue is an important clinical problem because acquired skeletal muscle weakness can increase the duration of hospitalization, result in exercise limitation, and contribute to a poor quality of life. Importantly, skeletal muscle atrophy is also associated with increased morbidity and mortality of patients. Therefore, improving our understanding of the mechanism(s) responsible for skeletal muscle weakness and fatigue in patients is a required first step to develop clinical protocols to prevent these skeletal muscle problems. This review will highlight the consequences and potential mechanisms responsible for skeletal muscle atrophy and fatigue in patients suffering from acute critical illness, cancer, chronic inflammatory diseases, and neurological disorders. PMID:27128663

Technologies as support tools for persons with autistic spectrum disorder: a systematic review.

PubMed

Aresti-Bartolome, Nuria; Garcia-Zapirain, Begonya

2014-08-04

This study analyzes the technologies most widely used to work on areas affected by the Autistic Spectrum Disorder (ASD). Technologies can focus on the strengths and weaknesses of this disorder as they make it possible to create controlled environments, reducing the anxiety produced by real social situations. Extensive research has proven the efficiency of technologies as support tools for therapy and their acceptation by ASD sufferers and the people who are with them on a daily basis. This article is organized by the types of systems developed: virtual reality applications, telehealth systems, social robots and dedicated applications, all of which are classified by the areas they center on: communication, social learning and imitation skills and other ASD-associated conditions. 40.5% of the research conducted is found to be focused on communication as opposed to 37.8% focused on learning and social imitation skills and 21.6% which underlines problems associated with this disorder. Although most of the studies reveal how useful these tools are in therapy, they are generic tools for ASD sufferers in general, which means there is a lack of personalised tools to meet each person's needs.

Technologies as Support Tools for Persons with Autistic Spectrum Disorder: A Systematic Review

PubMed Central

Aresti-Bartolome, Nuria; Garcia-Zapirain, Begonya

2014-01-01

This study analyzes the technologies most widely used to work on areas affected by the Autistic Spectrum Disorder (ASD). Technologies can focus on the strengths and weaknesses of this disorder as they make it possible to create controlled environments, reducing the anxiety produced by real social situations. Extensive research has proven the efficiency of technologies as support tools for therapy and their acceptation by ASD sufferers and the people who are with them on a daily basis. This article is organized by the types of systems developed: virtual reality applications, telehealth systems, social robots and dedicated applications, all of which are classified by the areas they center on: communication, social learning and imitation skills and other ASD-associated conditions. 40.5% of the research conducted is found to be focused on communication as opposed to 37.8% focused on learning and social imitation skills and 21.6% which underlines problems associated with this disorder. Although most of the studies reveal how useful these tools are in therapy, they are generic tools for ASD sufferers in general, which means there is a lack of personalised tools to meet each person’s needs. PMID:25093654

Good Use of a "Bad" Metaphor: Entropy as Disorder

ERIC Educational Resources Information Center

Haglund, Jesper

2017-01-01

Entropy is often introduced to students through the use of the disorder metaphor. However, many weaknesses and limitations of this metaphor have been identified, and it has therefore been argued that it is more harmful than useful in teaching. For instance, under the influence of the disorder metaphor, students tend to focus on spatial…

Children with central and peripheral neurologic disorders have distinguishable patterns of dysphagia on videofluoroscopic swallow study.

PubMed

van den Engel-Hoek, Lenie; Erasmus, Corrie E; van Hulst, Karen C M; Arvedson, Joan C; de Groot, Imelda J M; de Swart, Bert J M

2014-05-01

To determine whether findings on videofluoroscopic swallow studies reveal different patterns of dysphagia between children with central and peripheral neurologic disorders, a retrospective study of 118 videofluoroscopic swallow studies was completed. There were 3 groups: cerebral palsy with only spastic features (n = 53), cerebral palsy with dyskinetic features (n = 34), and neuromuscular disorders (myotonic dystrophy I, n = 5; spinal muscular atrophy I-II, n = 8; Duchenne muscular dystrophy, n = 8; other neuromuscular disorder, n = 10). Interpretation of the videofluoroscopic swallow studies was not blinded. The video fluoroscopic swallow study findings were compared dichotomously between the groups. Children with cerebral palsy demonstrated dysphagia in 1 or all phases of swallowing. In neuromuscular disorder, muscle weakness results in pharyngeal residue after swallow. The underlying swallowing problem in neuromuscular disorder is muscle weakness whereas that in cerebral palsy is more complex, having to do with abnormal control of swallowing. This study serves as a first exploration on specific characteristics of swallowing in different neurologic conditions and will help clinicians anticipate what they might expect.

Peripheral Nerve Disorders

MedlinePlus

... outlet syndrome. In some cases, like complex regional pain syndrome and brachial plexus injuries, the problem begins after an injury. Some people are born with peripheral nerve disorders. Symptoms often start gradually, and then ... Burning or tingling Muscle weakness Sensitivity to touch ...

Deficit in visual temporal integration in autism spectrum disorders.

PubMed

Nakano, Tamami; Ota, Haruhisa; Kato, Nobumasa; Kitazawa, Shigeru

2010-04-07

Individuals with autism spectrum disorders (ASD) are superior in processing local features. Frith and Happe conceptualize this cognitive bias as 'weak central coherence', implying that a local enhancement derives from a weakness in integrating local elements into a coherent whole. The suggested deficit has been challenged, however, because individuals with ASD were not found to be inferior to normal controls in holistic perception. In these opposing studies, however, subjects were encouraged to ignore local features and attend to the whole. Therefore, no one has directly tested whether individuals with ASD are able to integrate local elements over time into a whole image. Here, we report a weakness of individuals with ASD in naming familiar objects moved behind a narrow slit, which was worsened by the absence of local salient features. The results indicate that individuals with ASD have a clear deficit in integrating local visual information over time into a global whole, providing direct evidence for the weak central coherence hypothesis.

Myotonic dystrophytype 1 - report of non-24-h sleep-wake disorder with excessive daytime sleepiness.

PubMed

Filho, Lucio Huebra Pimentel; Gomes, Ana Carolina Dias; Gonçalves, Bruno; Tufik, Sergio; Coelho, Fernando Morgadinho

2018-05-15

Myotonic dystrophy (MD) is a neuromuscular disease with myotonia, progressive weakness, and involvement of CNS, heart, and gastrointestinal system. Excessive daytime sleepiness (EDS) in myotonic dystrophy type 1 (MD1) is related to sleep breathing diseases, restless leg syndrome, periodic limb movements during sleep and narcoleptic-like phenotype. However, authors highlight a central dysfunction of sleep regulation. We describe a 26-year-old, female, MD1 patient with EDS. Sleep diary/actigraphy evidenced two different circadian periods with values of 1442 and 1522 min. Agomelatine, 50 mg at night, was prescribed with improvement of the circadian rhythm and complaints of sleepiness. The identification of unanticipated causes of EDS, such as circadian rhythm disorders permits an appropriated treatment. As we know, it is the first relate of non-24-h sleep-wake disorder in patient with MD1. Sleep diary and actigraphy could be good options to investigate sleep-wake cycle disorder in patients with MD and EDS.

Ethical issues raised in addressing the needs of people with serious mental disorders in complex emergencies.

PubMed

Wissow, Lawrence S; Rutkow, Lainie; Kass, Nancy E; Rabins, Peter V; Vernick, Jon S; Hodge, James G

2012-03-01

Recent manmade and natural disasters highlight weaknesses in the public health systems designed to protect populations from harm and minimize disruption of the social and built environments. Emergency planning and response efforts have, as a result, focused largely on ensuring populations' physical well-being during and after a disaster. Many public health authorities, including the World Health Organization, have recognized the importance of addressing both mental and physical health concerns in emergency plans. Individuals with mental disorders represent a notable proportion of the overall population, and anticipating their needs is critical to comprehensive emergency planning and response efforts. Because people with serious mental disorders historically have been stigmatized, and many individuals with mental disorders may be unable to care for themselves, ethical guidance may be of assistance to those engaged in emergency planning and response. This article considers several broad categories of ethical issues that arise during emergencies for people with serious mental disorders and offers recommendations for ways in which emergency planners and other stakeholders can begin to address these ethical challenges.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iconaru, Luigi I.; Ban, David; Bharatham, Kavitha

In disordered proteins we see that they are highly prevalent in biological systems. They control myriad signaling and regulatory processes, and their levels and/or cellular localization are often altered in human disease. In contrast to folded proteins, disordered proteins, due to conformational heterogeneity and dynamics, are not considered viable drug targets. We challenged this paradigm by identifying through NMR-based screening small molecules that bound specifically, albeit weakly, to the disordered cell cycle regulator, p27 Kip1 (p27). Moreover, two groups of molecules bound to sites created by transient clusters of aromatic residues within p27. Conserved chemical features within these two groupsmore » of small molecules exhibited complementarity to their binding sites within p27, establishing structure-activity relationships for small molecule: disordered protein interactions. Finally, one compound counteracted the Cdk2/cyclin A inhibitory function of p27 in vitro, providing proof-of- principle that small molecules can inhibit the function of a disordered protein (p27) through sequestration in a conformation incapable of folding and binding to a natural regulatory target (Cdk2/cyclin A).« less

Effect of streptozotocin-induced diabetes on motor representations in the motor cortex and corticospinal tract in rats.

PubMed

Muramatsu, Ken; Ikutomo, Masako; Tamaki, Toru; Shimo, Satoshi; Niwa, Masatoshi

2018-02-01

Motor disorders in patients with diabetes are associated with diabetic peripheral neuropathy, which can lead to symptoms such as lower extremity weakness. However, it is unclear whether central motor system disorders can disrupt motor function in patients with diabetes. In a streptozotocin-induced rat model of type 1 diabetes, we used intracortical microstimulation to evaluate motor representations in the motor cortex, recorded antidromic motor cortex responses to spinal cord stimulation to evaluate the function of corticospinal tract (CST) axons, and used retrograde labeling to evaluate morphological alterations of CST neurons. The diabetic rats exhibited size reductions in the hindlimb area at 4 weeks and in trunk and forelimb areas after 13 weeks, with the hindlimb and trunk area reductions being the most severe. Other areas were unaffected. Additionally, we observed reduced antidromic responses in CST neurons with axons projecting to lumbar spinal segments (CST-L) but not in those with axons projecting to cervical segments (CST-C). This was consistent with the observation that retrograde-labeled CST-L neurons were decreased in number following tracer injection into the spinal cord in diabetic animals but that CST-C neurons were preserved. These results show that diabetes disrupts the CST system components controlling hindlimb and trunk movement. This disruption may contribute to lower extremity weakness in patients. Copyright © 2017 Elsevier B.V. All rights reserved.

Is bruxism a disorder or a behaviour? Rethinking the international consensus on defining and grading of bruxism

PubMed Central

RAPHAEL, K. G.; SANTIAGO, V.; LOBBEZOO, F.

2017-01-01

Summary Inspired by the international consensus on defining and grading of bruxism (Lobbezoo F, Ahlberg J, Glaros AG, Kato T, Koyano K, Lavigne GJ et al. J Oral Rehabil. 2013;40:2), this commentary examines its contribution and underlying assumptions for defining sleep bruxism (SB). The consensus’ parsimonious redefinition of bruxism as a behaviour is an advance, but we explore an implied question: might SB be more than behaviour? Behaviours do not inherently require clinical treatment, making the consensus-proposed ‘diagnostic grading system’ inappropriate. However, diagnostic grading might be useful, if SB were considered a disorder. Therefore, to fully appreciate the contribution of the consensus statement, we first consider standards and evidence for determining whether SB is a disorder characterised by harmful dysfunction or a risk factor increasing probability of a disorder. Second, the strengths and weaknesses of the consensus statement’s proposed ‘diagnostic grading system’ are examined. The strongest evidence-to-date does not support SB as disorder as implied by ‘diagnosis’. Behaviour alone is not diagnosed; disorders are. Considered even as a grading system of behaviour, the proposed system is weakened by poor sensitivity of self-report for direct polysomnographic (PSG)-classified SB and poor associations between clinical judgments of SB and portable PSG; reliance on dichotomised reports; and failure to consider SB behaviour on a continuum, measurable and definable through valid behavioural observation. To date, evidence for validity of self-report or clinician report in placing SB behaviour on a continuum is lacking, raising concerns about their potential utility in any bruxism behavioural grading system, and handicapping future study of whether SB may be a useful risk factor for, or itself a disorder requiring treatment. PMID:27283599

Liquid structure of the urea-water system studied by dielectric spectroscopy.

PubMed

Hayashi, Yoshihito; Katsumoto, Yoichi; Omori, Shinji; Kishii, Noriyuki; Yasuda, Akio

2007-02-08

Dielectric spectroscopy measurements for aqueous urea solutions were performed at 298 K through a concentration range from 0.5 to 9.0 M with frequencies between 200 MHz and 40 GHz. Observed dielectric spectra were well represented by the superposition of two Debye type relaxation processes attributable to the bulk-water clusters and the urea-water coclusters. Our quantitative analysis of the spectra shows that the number of hydration water molecules is approximately two per urea molecule for the lower concentration region below 5.0 M, while the previous molecular dynamics studies predicted approximately six water molecules. It was also indicated by those studies, however, that there are two types of hydration water molecule in urea solution, which are strongly and weakly associated to the urea molecule, respectively. Only the strongly associated water was distinguishable in our analysis, while the weakly associated water exhibited the same dynamic feature as bulk water. This implies that urea retains the weakly associated water in the tetrahedral structure and, thus, is not a strong structure breaker of water. We also verified the model of liquid water where water consists of two states: the icelike-ordered and dense-disordered phases. Our dielectric data did not agree with the theoretical prediction based on the two-phase model. The present work supports the argument that urea molecules can easily replace near-neighbor water in the hydrogen-bonding network and do not require the presence of the disordered phase of water to dissolve into water.

Moebius Sequence and Autism Spectrum Disorders--Less Frequently Associated than Formerly Thought

ERIC Educational Resources Information Center

Briegel, Wolfgang; Schimek, Martina; Kamp-Becker, Inge

2010-01-01

Moebius sequence is a rare congenital disorder usually defined as a combination of facial weakness with impairment of ocular abduction. It is questionable, whether there is a strong association of the sequence with autism spectrum disorders (ASDs) as suggested in some earlier case reports and studies. Twenty-two participants with Moebius sequence…

[Hereditary motor and sensory Lom-neuropathy--first Hungarian case report].

PubMed

Szabó, Antal; Siska, Eva; Molnár, Mária Judit

2007-01-20

Hereditary motor and sensory neuropathy-Lom is an autosomal recessive disorder of the peripheral nervous system, which occurs only in the european Roma population. The symptoms start in the first decade with slowly progressive gait disturbance, weakness and wasting of distal upper extremity muscles, joint deformities and hearing loss develop later in the second and third decades. This disorder is caused by a homozygous missense mutation of the NDRG1 gene, located in the 8q24 region. The Schwann cell dysfunction is most probably caused by altered lipid metabolism as a consequence of the NDRG1 mutation. Molecular genetic testing can be a first diagnostic step among roma individuals showing a Lom neuropathy phenotype, making evaluation of such patients and also genetic counselling faster and easier. Screening for hereditary neuromuscular disorders in this genetically isolated community may become an important public health issue in the near future.

Neurological features and management of Wilson disease in children: an evaluation of 12 cases.

PubMed

Bayram, Ayşe Kaçar; Gümüş, Hakan; Arslan, Duran; Özçora, Güldemet Kaya; Kumandaş, Sefer; Karacabey, Neslihan; Canpolat, Mehmet; Per, Hüseyin

2016-03-01

Wilson's disease is an autosomal recessive disorder of copper metabolism which leads to copper overload in different tissues of the body. The aim of this study was to present the neurologic features of Wilson's disease and to assess the clinical course of neurological findings in children receiving anti-copper treatment. Twelve children with a diagnosis of Wilson's disease and findings of central nervous system involvement who were followed up in the Department of Pediatric Neurology and Pediatric Gastroenterology of the School of Medicine at Erciyes University were enrolled in the study. The study cases consisted of five boys (42%) and seven girls (58%). The mean age at the time of diagnosis was 9.9±3.4 years (5-15 years). The mean duration of follow-up was 49.0±36.4 months (15-128 months). Neurological findings at presentation included headache in seven cases (58%), tremor in seven cases (58%), dystonia in three cases (25%), ataxia in two cases (17%), dizziness in two cases (17%), numbness in the hands and acute weakness in one case (8%) and syncope in one case (8%). Headache, dizziness, syncope, numbness in hands and acute weakness symptoms resolved completely within six months after receiving treatment. Movement disorders either decreased or remained stable in seven of the eight cases. However, one patient developed progressively worsening dystonia despite to all treatments. Wilson's disease can be manifested with signs and symptoms of central nervous system in the childhood. Wilson's disease should be considered in all children presenting with movement disorders. A complete neurological assessment should be carried out in all cases with Wilson's disease.

Neurological features and management of Wilson disease in children: an evaluation of 12 cases

PubMed Central

Bayram, Ayşe Kaçar; Gümüş, Hakan; Arslan, Duran; Özçora, Güldemet Kaya; Kumandaş, Sefer; Karacabey, Neslihan; Canpolat, Mehmet; Per, Hüseyin

2016-01-01

Aim: Wilson’s disease is an autosomal recessive disorder of copper metabolism which leads to copper overload in different tissues of the body. The aim of this study was to present the neurologic features of Wilson’s disease and to assess the clinical course of neurological findings in children receiving anti-copper treatment. Material and Methods: Twelve children with a diagnosis of Wilson’s disease and findings of central nervous system involvement who were followed up in the Department of Pediatric Neurology and Pediatric Gastroenterology of the School of Medicine at Erciyes University were enrolled in the study. Results: The study cases consisted of five boys (42%) and seven girls (58%). The mean age at the time of diagnosis was 9.9±3.4 years (5–15 years). The mean duration of follow-up was 49.0±36.4 months (15–128 months). Neurological findings at presentation included headache in seven cases (58%), tremor in seven cases (58%), dystonia in three cases (25%), ataxia in two cases (17%), dizziness in two cases (17%), numbness in the hands and acute weakness in one case (8%) and syncope in one case (8%). Headache, dizziness, syncope, numbness in hands and acute weakness symptoms resolved completely within six months after receiving treatment. Movement disorders either decreased or remained stable in seven of the eight cases. However, one patient developed progressively worsening dystonia despite to all treatments. Conclusions: Wilson’s disease can be manifested with signs and symptoms of central nervous system in the childhood. Wilson’s disease should be considered in all children presenting with movement disorders. A complete neurological assessment should be carried out in all cases with Wilson’s disease. PMID:27103860

Three-state Potts model on non-local directed small-world lattices

NASA Astrophysics Data System (ADS)

Ferraz, Carlos Handrey Araujo; Lima, José Luiz Sousa

2017-10-01

In this paper, we study the non-local directed Small-World (NLDSW) disorder effects in the three-state Potts model as a form to capture the essential features shared by real complex systems where non-locality effects play a important role in the behavior of these systems. Using Monte Carlo techniques and finite-size scaling analysis, we estimate the infinite lattice critical temperatures and the leading critical exponents in this model. In particular, we investigate the first- to second-order phase transition crossover when NLDSW links are inserted. A cluster-flip algorithm was used to reduce the critical slowing down effect in our simulations. We find that for a NLDSW disorder densities p

Specific heat and magnetic susceptibility of CeNiSn doped with Rh.

PubMed

Slebarski, A; Maple, M B; Fijałkowski, M; Goraus, J

2010-04-28

CeNiSn is known as a semimetallic system with a small pseudogap at the Fermi energy. We investigate the effect of Rh doping on the Kondo insulator CeNiSn by means of measurements of ac magnetic susceptibility and specific heat. We show that the formation of the Kondo insulator narrow gap in CeNi(1 - x)Rh(x)Sn is associated with disorder-induced f-electron localization. For doped CeNiSn with x ≤ 0.06, the electrical resistivity data follow an activation and variable range hopping behaviour at low T, consistent with weak disorder and localization, while C/T is large, which is not a common feature of Kondo insulators. For x > 0.06, the system is metallic and exhibits non-Fermi liquid behaviour with magnetic susceptibility χ ∼ T( - n) with n ∼ 0.4 and electrical resistivity ρ ∼ T.

Chiral Spin Order in Kondo-Heisenberg Systems

NASA Astrophysics Data System (ADS)

Tsvelik, A. M.; Yevtushenko, O. M.

2017-12-01

We demonstrate that low dimensional Kondo-Heisenberg systems, consisting of itinerant electrons and localized magnetic moments (Kondo impurities), can be used as a principally new platform to realize scalar chiral spin order. The underlying physics is governed by a competition of the Ruderman-Kittel-Kosuya-Yosida (RKKY) indirect exchange interaction between the local moments with the direct Heisenberg one. When the direct exchange is weak and RKKY dominates, the isotropic system is in the disordered phase. A moderately large direct exchange leads to an Ising-type phase transition to the phase with chiral spin order. Our finding paves the way towards pioneering experimental realizations of the chiral spin liquid in systems with spontaneously broken time-reversal symmetry.

Treatment with acetazolamide of brain-stem and spinal paroxysmal disturbances in multiple sclerosis.

PubMed Central

Voiculescu, V; Pruskauer-Apostol, B; Alecu, C

1975-01-01

Nine cases of multiple sclerosis with paroxysmal disorders were treated with acetazolamide. In most cases a brain-stem origin of the seizures was suggested by their particular pattern: crossed syndromes (facial spasm associated with contralateral weakness of the arm and leg, paroxysmal paraesthesiae in one side of the face and weakness of the contralateral leg), paroxysmal dysarthria, and ataxia. One patient with a Brown-Sequard syndrome complained of paroxysmal paraesthesiae in the lower limbs, for which a spinal origin was admitted. In all patients the paroxysmal disorders were promptly suppressed or markedly reduced by acetazolamide. PMID:1151400

Is Attention Impaired in ADHD?

ERIC Educational Resources Information Center

Wilding, John

2005-01-01

Explanations of Attention Deficit Hyperactivity Disorder (ADHD) in terms of a weakness in Executive Function (EF) or related concepts, such as inhibition, are briefly reviewed. Some alternative views are considered, in particular a proposal by Manly and others that ADHD is a weakness primarily of sustained attention (plus control of attention),…

Disordered animal multilayer reflectors and the localization of light

PubMed Central

Jordan, T. M.; Partridge, J. C.; Roberts, N. W.

2014-01-01

Multilayer optical reflectors constructed from ‘stacks’ of alternating layers of high and low refractive index dielectric materials are present in many animals. For example, stacks of guanine crystals with cytoplasm gaps occur within the skin and scales of fish, and stacks of protein platelets with cytoplasm gaps occur within the iridophores of cephalopods. Common to all these animal multilayer reflectors are different degrees of random variation in the thicknesses of the individual layers in the stack, ranging from highly periodic structures to strongly disordered systems. However, previous discussions of the optical effects of such thickness disorder have been made without quantitative reference to the propagation of light within the reflector. Here, we demonstrate that Anderson localization provides a general theoretical framework to explain the common coherent interference and optical properties of these biological reflectors. Firstly, we illustrate how the localization length enables the spectral properties of the reflections from more weakly disordered ‘coloured’ and more strongly disordered ‘silvery’ reflectors to be explained by the same physical process. Secondly, we show how the polarization properties of reflection can be controlled within guanine–cytoplasm reflectors, with an interplay of birefringence and thickness disorder explaining the origin of broadband polarization-insensitive reflectivity. PMID:25339688

Idiopathic Inflammatory Myopathies

PubMed Central

Barohn, Richard J.; Amato, Anthony

2014-01-01

The idiopathic inflammatory myopathies (IIM) consist of rare heterogenous autoimmune disorders that present with marked proximal and symmetric muscle weakness, except for distal and asymmetric weakness in inclusion body myositis (IBM). Besides frequent creatine kinase (CK) elevation, the electromyogram confirms the presence of an irritative myopathy. Extramuscular involvement affects a significant number of cases with interstitial lung disease (ILD), cutaneous in dermatomyositis (DM), systemic or joint manifestations and increased risk of malignancy especially in DM. Myositis specific autoantibodies influence phenotype of the IIM. Jo-1 antibodies are frequently associated with ILD and the newly described HMG-CoA reductase antibodies are characteristic of autoimmune necrotizing myopathy (NM). Muscle pathology ranges from inflammatory exudates of variable distribution, to intact muscle fiber invasion, necrosis, phagocytosis and in the case of IBM rimmed vacuoles and protein deposits. Despite many similarities, the IIM are a quite heterogeneous from the histopathological and pathogenetic standpoints in addition to some clinical and treatment-response difference. The field has witnessed significant advances in our understanding of pathophysiology and treatment of these rare disorders. In this review, we focus on DM, polymyositis (PM) and NM and examine current and promising therapies. The reader interested in more details on IBM is referred to the corresponding chapter in this issue. PMID:25037081

Disorder effect on the Friedel oscillations in a one-dimensional Mott insulator

NASA Astrophysics Data System (ADS)

Weiss, Y.; Goldstein, M.; Berkovits, R.

2007-07-01

The Friedel oscillations resulting from coupling a quantum dot to one edge of a disordered one-dimensional wire in the Mott insulator regime are calculated numerically using the density matrix renormalization group method. By investigating the influence of a constant weak disorder on the Friedel oscillations decay we find that the effect of disorder is reduced by increasing the interaction strength. This behavior is opposite to the recently reported influence of disorder in the Anderson insulator regime.

Oral Language Impairments in Developmental Disorders Characterized by Language Strengths: A Comparison of Asperger Syndrome and Nonverbal Learning Disabilities

ERIC Educational Resources Information Center

Stothers, M. E.; Cardy, J. Oram

2012-01-01

Asperger syndrome (AS) and nonverbal learning disabilities (NLD) are developmental disorders in which linguistic ability is reported to be stronger than in disorders from which they must be distinguished for diagnosis. Children and adults with AS and NLD share pragmatic weaknesses, atypical social behaviours, and some cognitive features. To date,…

Self-averaging and weak ergodicity breaking of diffusion in heterogeneous media

NASA Astrophysics Data System (ADS)

Russian, Anna; Dentz, Marco; Gouze, Philippe

2017-08-01

Diffusion in natural and engineered media is quantified in terms of stochastic models for the heterogeneity-induced fluctuations of particle motion. However, fundamental properties such as ergodicity and self-averaging and their dependence on the disorder distribution are often not known. Here, we investigate these questions for diffusion in quenched disordered media characterized by spatially varying retardation properties, which account for particle retention due to physical or chemical interactions with the medium. We link self-averaging and ergodicity to the disorder sampling efficiency Rn, which quantifies the number of disorder realizations a noise ensemble may sample in a single disorder realization. Diffusion for disorder scenarios characterized by a finite mean transition time is ergodic and self-averaging for any dimension. The strength of the sample to sample fluctuations decreases with increasing spatial dimension. For an infinite mean transition time, particle motion is weakly ergodicity breaking in any dimension because single particles cannot sample the heterogeneity spectrum in finite time. However, even though the noise ensemble is not representative of the single-particle time statistics, subdiffusive motion in q ≥2 dimensions is self-averaging, which means that the noise ensemble in a single realization samples a representative part of the heterogeneity spectrum.

An update on the management of chronic inflammatory demyelinating polyneuropathy

PubMed Central

2012-01-01

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune mediated disorder of the peripheral nervous system with clinical features that include weakness, sensory loss, imbalance, pain and impaired ambulation which may lead to substantial disability. This review highlights current treatment strategies for CIDP, how best to utilize proven therapies such as intravenous immunoglobulin, oral prednisone, pulse dexamethasone, and plasma exchange, and when and how to use alternative immunosuppressive agents when first-line therapies are ineffective or poorly tolerated. PMID:23139706

Self-energy functional theory with symmetry breaking for disordered lattice bosons

NASA Astrophysics Data System (ADS)

Hügel, Dario; Strand, Hugo U. R.; Pollet, Lode

2018-07-01

We extend the self-energy functional theory to the case of interacting lattice bosons in the presence of symmetry breaking and quenched disorder. The self-energy functional we derive depends only on the self-energies of the disorder-averaged propagators, allowing for the construction of general non-perturbative approximations. Using a simple single-site reference system with only three variational parameters, we are able to reproduce numerically exact quantum Monte Carlo (QMC) results on local observables of the Bose–Hubbard model with box disorder with high accuracy. At strong interactions, the phase boundaries are reproduced qualitatively but shifted with respect to the ones observed with QMC due to the extremely low condensate fraction in the superfluid phase. Deep in the strongly-disordered weakly-interacting regime, the simple reference system employed is insufficient and no stationary solutions can be found within its restricted variational subspace. By systematically analyzing thermodynamical observables and the spectral function, we find that the strongly interacting Bose glass is characterized by different regimes, depending on which local occupations are activated as a function of the disorder strength. We find that the particles delocalize into isolated superfluid lakes over a strongly localized background around maximally-occupied sites whenever these sites are particularly rare. Our results indicate that the transition from the Bose glass to the superfluid phase around unit filling at strong interactions is driven by the percolation of superfluid lakes which form around doubly occupied sites.

Neuroanatomy of conversion disorder: towards a network approach.

PubMed

Conejero, Ismael; Thouvenot, Eric; Abbar, Mocrane; Mouchabac, Stéphane; Courtet, Philippe; Olié, Emilie

2018-06-27

The pathophysiology of conversion disorder is not well understood, although studies using functional brain imaging in patients with motor and sensory symptoms are progressively increasing. We conducted a systematic review of the literature with the aim of summarising the available data on the neuroanatomical features of this disorder. We also propose a general model of the neurobiological disturbance in motor conversion disorder. We systematically searched articles in Medline using the Medical Subject Headings terms '(conversion disorder or hysterical motor disorder) and (neuropsychology or cognition) or (functional magnetic resonance imaging or positron emission tomography or neuroimaging) or (genetics or polymorphisms or epigenetics) or (biomarkers or biology)', following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two authors independently reviewed the retrieved records and abstracts, assessed the exhaustiveness of data abstraction, and confirmed the quality rating. Analysis of the available literature data shows that multiple specialised brain networks (self-agency, action monitoring, salience system, and memory suppression) influence action selection and modulate supplementary motor area activation. Some findings suggest that conceptualisation of movement and motor intention is preserved in patients with limb weakness. More studies are needed to fully understand the brain alterations in conversion disorders and pave the way for the development of effective therapeutic strategies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuchinskii, E. Z., E-mail: kuchinsk@iep.uran.ru; Kuleeva, N. A.; Sadovskii, M. V., E-mail: sadovski@iep.uran.ru

We derive a Ginzburg–Landau (GL) expansion in the disordered attractive Hubbard model within the combined Nozieres–Schmitt-Rink and DMFT+Σ approximation. Restricting ourselves to the homogeneous expansion, we analyze the disorder dependence of GL expansion coefficients for a wide range of attractive potentials U, from the weak BCS coupling region to the strong-coupling limit, where superconductivity is described by Bose–Einstein condensation (BEC) of preformed Cooper pairs. We show that for the a semielliptic “bare” density of states of the conduction band, the disorder influence on the GL coefficients A and B before quadratic and quartic terms of the order parameter, as wellmore » as on the specific heat discontinuity at the superconducting transition, is of a universal nature at any strength of the attractive interaction and is related only to the general widening of the conduction band by disorder. In general, disorder growth increases the values of the coefficients A and B, leading either to a suppression of the specific heat discontinuity (in the weak-coupling limit), or to its significant growth (in the strong-coupling region). However, this behavior actually confirms the validity of the generalized Anderson theorem, because the disorder dependence of the superconducting transition temperature T{sub c}, is also controlled only by disorder widening of the conduction band (density of states).« less

Lexical Processing in Toddlers with ASD: Does Weak Central Coherence Play a Role?

ERIC Educational Resources Information Center

Ellis Weismer, Susan; Haebig, Eileen; Edwards, Jan; Saffran, Jenny; Venker, Courtney E.

2016-01-01

This study investigated whether vocabulary delays in toddlers with autism spectrum disorders (ASD) can be explained by a cognitive style that prioritizes processing of detailed, local features of input over global contextual integration--as claimed by the weak central coherence (WCC) theory. Thirty toddlers with ASD and 30 younger,…

Myasthenia Gravis and the Myasthenic Syndrome

PubMed Central

Herrmann, Christian

1970-01-01

Two disorders of neuromuscular transmission producing muscle weakness and easy fatigability which may confront the physician are myasthenia gravis and the myasthenic syndrome. The former has early symptoms and signs of oculobulbar and then extremity weakness with rapid decline of action potential and contractile strength with repetitive use and nerve-muscle stimulation. Anticholinesterases improve strength. The myasthenic syndrome has early symptoms and signs of pelvic girdle, pectoral girdle and proximal limb muscle weakness. This is worst when first starting to use or carry out nerve muscle stimulation in the rested muscles. It improves significantly for a time with use or on rapid stimulation, and then declines with continued activation. Deep tendon reflexes are sluggish or absent. Small cell carcinoma of the lung is often associated. Guanidine improves the strength. Other features and possible underlying mechanisms of the two disorders help to differentiate and treat them. PMID:5457513

Kinetic theory of nonlinear diffusion in a weakly disordered nonlinear Schrödinger chain in the regime of homogeneous chaos.

PubMed

Basko, D M

2014-02-01

We study the discrete nonlinear Schröinger equation with weak disorder, focusing on the regime when the nonlinearity is, on the one hand, weak enough for the normal modes of the linear problem to remain well resolved but, on the other, strong enough for the dynamics of the normal mode amplitudes to be chaotic for almost all modes. We show that in this regime and in the limit of high temperature, the macroscopic density ρ satisfies the nonlinear diffusion equation with a density-dependent diffusion coefficient, D(ρ) = D(0)ρ(2). An explicit expression for D(0) is obtained in terms of the eigenfunctions and eigenvalues of the linear problem, which is then evaluated numerically. The role of the second conserved quantity (energy) in the transport is also quantitatively discussed.

[What is the contribution of Stewart's concept in acid-base disorders analysis?].

PubMed

Quintard, H; Hubert, S; Ichai, C

2007-05-01

To explain the different approaches for interpreting acid-base disorders; to develop the Stewart model which offers some advantages for the pathophysiological understanding and the clinical interpretation of acid-base imbalances. Record of french and english references from Medline data base. The keywords were: acid-base balance, hyperchloremic acidosis, metabolic acidosis, strong ion difference, strong ion gap. Data were selected including prospective and retrospective studies, reviews, and case reports. Acid-base disorders are commonly analysed by using the traditional Henderson-Hasselbalch approach which attributes the variations in plasma pH to the modifications in plasma bicarbonates or PaCO2. However, this approach seems to be inadequate because bicarbonates and PaCO2 are completely dependent. Moreover, it does not consider the role of weak acids such as albuminate, in the determination of plasma pH value. According to the Stewart concept, plasma pH results from the degree of plasma water dissociation which is determined by 3 independent variables: 1) strong ion difference (SID) which is the difference between all the strong plasma cations and anions; 2) quantity of plasma weak acids; 3) PaCO2. Thus, metabolic acid-base disorders are always induced by a variation in SID (decreased in acidosis) or in weak acids (increased in acidosis), whereas respiratory disorders remains the consequence of a change in PaCO2. These pathophysiological considerations are important to analyse complex acid-base imbalances in critically ill patients. For example, due to a decrease in weak acids, hypoalbuminemia increases SID which may counter-balance a decrease in pH and an elevated anion gap. Thus if using only traditional tools, hypoalbuminemia may mask a metabolic acidosis, because of a normal pH and a normal anion gap. In this case, the association of metabolic acidosis and alkalosis is only expressed by respectively a decreased SID and a decreased weak acids concentration. This concept allows to establish the relationship between hyperchloremic acidosis and infusion of solutes which contain large concentration of chloride such as NaCl 0.9%. Finally, the Stewart concept permits to understand that sodium bicarbonate as well as sodium lactate induces plasma alkalinization. In fact, sodium remains in plasma, whereas anion (lactate or bicarbonate) are metabolized leading to an increase in plasma SID. Due to its simplicity, the traditional Henderson-Hasselbalch approach of acid-base disorders, remains commonly used. However, it gives an inadequate pathophysiological analysis which may conduct to a false diagnosis, especially with complex acid-base imbalances. Despite its apparent complexity, the Stewart concept permits to understand precisely the mechanisms of acid-base disorders. It has to become the most appropriate approach to analyse complex acid-base abnormalities.

[Studies of time-course changes in human body balance after ingestion of long-acting hypnotics].

PubMed

Nakamura, Masahiro; Ishii, Masanori; Niwa, Yoji; Yamazaki, Momoko; Ito, Hiroshi

2004-02-01

Falling accidents are a serious nocosomial problem, with balance disorders after the ingestion of hypnotics said to be a cause. Based on the results of animal studies, it was postulated that this problem involves the muscle relaxation that is a pharmacological effect of benzodiazepines (BZP). No reports have, to our knowledge, been made of time-course changes in human body balance after ingestion of hypnotics. Accordingly, we used quazepam (Doral), a long-acting hypnotic considered to show comparatively weak muscle relaxation, to study static balance after drug ingestion in human volunteers. Briefly, informed consent was obtained from 8 healthy adults, then a gait analytic system (Gangas) was used to test static balance after drug ingestion (Mann and Romberg tests). We also measured circulating drug concentration over time. Our results showed that balance disorders occurred after quazepam ingestion with an unstable posture particularly striking. Given the function of quazepam receptors, it is difficult to surmise that balance disorders after drug ingestion were due to the drug's muscle relaxation. We surmised that inhibition from the central nervous system in connection with nerves awakening was involved. We found a strong correlation between the manifestation of balance disorders after drug ingestion and circulating drug concentration.

Variable-Range Hopping through Marginally Localized Phonons

NASA Astrophysics Data System (ADS)

Banerjee, Sumilan; Altman, Ehud

2016-03-01

We investigate the effect of coupling Anderson localized particles in one dimension to a system of marginally localized phonons having a symmetry protected delocalized mode at zero frequency. This situation is naturally realized for electrons coupled to phonons in a disordered nanowire as well as for ultracold fermions coupled to phonons of a superfluid in a one-dimensional disordered trap. To determine if the coupled system can be many-body localized we analyze the phonon-mediated hopping transport for both the weak and strong coupling regimes. We show that the usual variable-range hopping mechanism involving a low-order phonon process is ineffective at low temperature due to discreteness of the bath at the required energy. Instead, the system thermalizes through a many-body process involving exchange of a diverging number n ∝-log T of phonons in the low temperature limit. This effect leads to a highly singular prefactor to Mott's well-known formula and strongly suppresses the variable range hopping rate. Finally, we comment on possible implications of this physics in higher dimensional electron-phonon coupled systems.

Spin Hall Effect and Weak Antilocalization in Graphene/Transition Metal Dichalcogenide Heterostructures.

PubMed

Garcia, Jose H; Cummings, Aron W; Roche, Stephan

2017-08-09

We report on a theoretical study of the spin Hall Effect (SHE) and weak antilocalization (WAL) in graphene/transition metal dichalcogenide (TMDC) heterostructures, computed through efficient real-space quantum transport methods, and using realistic tight-binding models parametrized from ab initio calculations. The graphene/WS 2 system is found to maximize spin proximity effects compared to graphene on MoS 2 , WSe 2 , or MoSe 2 with a crucial role played by disorder, given the disappearance of SHE signals in the presence of strong intervalley scattering. Notably, we found that stronger WAL effects are concomitant with weaker charge-to-spin conversion efficiency. For further experimental studies of graphene/TMDC heterostructures, our findings provide guidelines for reaching the upper limit of spin current formation and for fully harvesting the potential of two-dimensional materials for spintronic applications.

Characterizing the Atomic Structure in Low Concentrations of Weakly Ordered, Weakly Scattering Materials Using the Pair Distribution Function

NASA Astrophysics Data System (ADS)

Terban, Maxwell W.

Nanoscale structural characterization is critical to understanding the physical underpinnings of properties and behavior in materials with technological applications. The work herein shows how the pair distribution function technique can be applied to x-ray total scattering data for material systems which weakly scatter x-rays, a typically difficult task due to the poor signal-to-noise obtained from the structures of interest. Characterization and structural modeling are demonstrated for a variety of molecular and porous systems, along with the detection and characterization of disordered, minority phases and components. In particular, reliable detection and quantitative analysis are demonstrated for nanocrystals of an active pharmaceutical ingredient suspended in dilute solution down to a concentration of 0.25 wt. %, giving a practical limit of detection for ordered nanoscale phases within a disordered matrix. Further work shows that minority nanocrystalline phases can be detected, fingerprinted, and modeled for mixed crystalline and amorphous systems of small molecules and polymers. The crystallization of amorphous lactose is followed under accelerated aging conditions. Melt quenching is shown to produce a different local structure than spray drying or freeze drying, along with increased resistance to crystallization. The initial phases which form in the spray dried formulation are identified as a mixture of polymorphs different from the final alpha-lactose monohydrate form. Hard domain formation in thermoplastic polyurethanes is also characterized as a function of methylene diphenyl diisocyanate and butanediol component ratio, showing that distinct and different hard phase structures can form and are solved by indexing with structures derived from molecular dynamics relaxation. In both cases, phase fractions can be quantified in the mixed crystalline and amorphous systems by fitting with both standards or structure models. Later chapters, demonstrate pair distribution characterization of particle incorporation, structure, and synthesis of nanoporous materials. Nanoparticle size distributions are extracted from platinum nanoparticles nucleating within a zeolite matrix through structural modeling, and validated by transmission electron microscope studies. The structure of zirconium phosphonate-phosphate unconventional metal organic framework is determined to consist of turbostratically disordered nanocrystalline layers of Zr-phenylphosphonate, and the local environment of terbium intercalated between the layers is found to resemble the local environment in scheelite-type terbium phosphate. Finally, the early stages of reaction between aqueous zinc dinitrate hexahydrate and methanolic 2-methylimidazole are characterized using in situ total scattering measurements, showing that secondary building units of tetrahedrally coordinated by 2-methylimidazole initially form upon reaction. Overall, the methodologies are developed and applied toward phase detection, identification, solution, and behavior in pharmaceuticals, polymers, and nanoporous materials along with advice for carrying out experiments and analysis on such materials such that they can be extended to other similar systems.

Hydrogen-Exchange Mass Spectrometry for the Study of Intrinsic Disorder in Proteins

PubMed Central

Balasubramaniam, Deepa; Komives, Elizabeth A.

2012-01-01

Amide hydrogen/deuterium exchange detected by mass spectrometry (HXMS) is seeing wider use for the identification of intrinsically disordered parts of proteins. In this review, we discuss examples of how discovery of intrinsically disordered regions and their removal can aid in structure determination, biopharmaceutical quality control, the characterization of how posttranslational modifications affect weak structuring of disordered regions, the study of coupled folding and binding, and the characterization of amyloid formation. PMID:23099262

Chiral Spin Order in Kondo-Heisenberg systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsvelik, A. M.; Yevtushenko, O. M.

We demonstrate that Kondo-Heisenberg systems, consisting of itinerant electrons and localized magnetic moments (Kondo impurities), can be used as a principally new platform to realize scalar chiral spin order. The underlying physics is governed by a competition of the Ruderman-Kittel- Kosuya-Yosida (RKKY) indirect exchange interaction between the local moments with the direct Heisenberg one. When the direct exchange is weak and RKKY dominates the isotropic system is in the disordered phase. A moderately large direct exchange leads to an Ising-type phase transition to the phase with chiral spin order. Our nding paves the way towards pioneering experimental realizations of themore » chiral spin liquid in low dimensional systems with spontaneously broken time reversal symmetry.« less

Chiral Spin Order in Kondo-Heisenberg systems

DOE PAGES

Tsvelik, A. M.; Yevtushenko, O. M.

2017-12-15

We demonstrate that Kondo-Heisenberg systems, consisting of itinerant electrons and localized magnetic moments (Kondo impurities), can be used as a principally new platform to realize scalar chiral spin order. The underlying physics is governed by a competition of the Ruderman-Kittel- Kosuya-Yosida (RKKY) indirect exchange interaction between the local moments with the direct Heisenberg one. When the direct exchange is weak and RKKY dominates the isotropic system is in the disordered phase. A moderately large direct exchange leads to an Ising-type phase transition to the phase with chiral spin order. Our nding paves the way towards pioneering experimental realizations of themore » chiral spin liquid in low dimensional systems with spontaneously broken time reversal symmetry.« less

Postoperative conversion disorder.

PubMed

Afolabi, Kola; Ali, Sameer; Gahtan, Vivian; Gorji, Reza; Li, Fenghua; Nussmeier, Nancy A

2016-05-01

Conversion disorder is a psychiatric disorder in which psychological stress causes neurologic deficits. A 28-year-old female surgical patient had uneventful general anesthesia and emergence but developed conversion disorder 1 hour postoperatively. She reported difficulty speaking, right-hand numbness and weakness, and right-leg paralysis. Neurologic examination and imaging revealed no neuronal damage, herniation, hemorrhage, or stroke. The patient mentioned failing examinations the day before surgery and discontinuing her prescribed antidepressant medication, leading us to diagnose conversion disorder, with eventual confirmation by neuroimaging and follow-up examinations. Copyright © 2016 Elsevier Inc. All rights reserved.

Electron-phonon mediated heat flow in disordered graphene

NASA Astrophysics Data System (ADS)

Chen, Wei; Clerk, Aashish A.

2012-09-01

We calculate the heat flux and electron-phonon thermal conductance in a disordered graphene sheet, going beyond a Fermi’s golden rule approach to fully account for the modification of the electron-phonon interaction by disorder. Using the Keldysh technique combined with standard impurity averaging methods in the regime kFl≫1 (where kF is the Fermi wave vector and l is the mean free path), we consider both scalar potential (i.e., deformation potential) and vector-potential couplings between electrons and phonons. We also consider the effects of electronic screening at the Thomas-Fermi level. We find that the temperature dependence of the heat flux and thermal conductance is sensitive to the presence of disorder and screening, and reflects the underlying chiral nature of electrons in graphene and the corresponding modification of their diffusive behavior. In the case of weak screening, disorder enhances the low-temperature heat flux over the clean system (changing the associated power law from T4 to T3), and the deformation potential dominates. For strong screening, both the deformation potential and vector-potential couplings make comparable contributions, and the low-temperature heat flux obeys a T5 power law.

Optimal dephasing for ballistic energy transfer in disordered linear chains

NASA Astrophysics Data System (ADS)

Zhang, Yang; Celardo, G. Luca; Borgonovi, Fausto; Kaplan, Lev

2017-11-01

We study the interplay between dephasing, disorder, and coupling to a sink on transport efficiency in a one-dimensional chain of finite length N , and in particular the beneficial or detrimental effect of dephasing on transport. The excitation moves along the chain by coherent nearest-neighbor hopping Ω , under the action of static disorder W and dephasing γ . The last site is coupled to an external acceptor system (sink), where the excitation can be trapped with a rate Γtrap. While it is known that dephasing can help transport in the localized regime, here we show that dephasing can enhance energy transfer even in the ballistic regime. Specifically, in the localized regime we recover previous results, where the optimal dephasing is independent of the chain length and proportional to W or W2/Ω . In the ballistic regime, the optimal dephasing decreases as 1 /N or 1 /√{N } , respectively, for weak and moderate static disorder. When focusing on the excitation starting at the beginning of the chain, dephasing can help excitation transfer only above a critical value of disorder Wcr, which strongly depends on the sink coupling strength Γtrap. Analytic solutions are obtained for short chains.

Disorders of lipid metabolism in muscle.

PubMed

Di Mauro, S; Trevisan, C; Hays, A

1980-01-01

At rest and during sustained exercise, lipids are the main source of energy for muscle. Free fatty acids become available to muscle from plasma free fatty acids and triglycerides, and from intracellular triglycride lipid droplets. Transport of long-chain fatty acyl groups into the mitochondria requires esterification and de-esterification with carnitine by the "twin" enzymes carnitine palmityltransferase (CPT) I and II, bound to the outer and inner faces of the inner mitochondrial membrane. Carnitine deficiency occurs in two clinical syndromes. (1) In the myopathic form, there is weakness; muscle biopsy shows excessive accumulation of lipid droplets; and the carnitine concentration is markedly decreased in muscle but normal in plasma. (2) In the systemic form, there are weakness and recurrent episodes of hepatic encephalopathy; muscle biopsy shows lipid storage; and the carnitine concentration is decreased in muscle, liver, and plasma. The etiology of carnitine deficiency is not known in either the myopathic or the systemic form, but administration of carnitine or corticosteroids has been beneficial in some patients. "Secondary" carnitine deficiency may occur in patients with malnutrition, liver disease, chronic hemodialysis, and, possibly, mitochondrial disorders. CPT deficiency causes recurrent myoglobinuria, usually precipitated by prolonged exercise or fasting. Muscle biopsy may be normal or show varying degrees of lipid storage. Genetic transmission is probably autosomal recessive, but the great male predominance (20/21) remains unexplained. In many cases, lipid storage myopathy is not accompanied by carnitine or CPT deficiency, and the biochemical error remains to be identified.

Local information processing in adults with high functioning autism and asperger syndrome: the usefulness of neuropsychological tests and self-reports.

PubMed

Spek, Annelies A; Scholte, Evert M; Van Berckelaer-Onnes, Ina A

2011-07-01

Local information processing in 42 adults with high functioning autism, 41 adults with Asperger syndrome and 41 neurotypical adults was examined. Contrary to our expectations, the disorder groups did not outperform the neurotypical group in the neuropsychological measures of local information processing. In line with our hypotheses, the self-reports did show higher levels of local information processing and a stronger tendency to use systemizing strategies in the two disorder groups. Absent and weak correlations were found between the self-reports and the two neuropsychological tasks in the three groups. The neuropsychological tests and the self-reports seem to measure different underlying constructs. The self-reports were most predictive of the presence of an autism spectrum diagnosis.

Evidence of Reduced Global Processing in Autism Spectrum Disorder

ERIC Educational Resources Information Center

Booth, Rhonda D. L.; Happé, Francesca G. E.

2018-01-01

Frith's original notion of 'weak central coherence' suggested that increased local processing in autism spectrum disorder (ASD) resulted from reduced global processing. More recent accounts have emphasised superior local perception and suggested intact global integration. However, tasks often place local and global processing in direct trade-off,…

Neuropsychological Profile in High Functioning Autism Spectrum Disorders

ERIC Educational Resources Information Center

Narzisi, Antonio; Muratori, Filippo; Calderoni, Sara; Fabbro, Franco; Urgesi, Cosimo

2013-01-01

A comprehensive investigation of the neuropsychological strengths and weaknesses of children with autism may help to better describe their cognitive abilities and to design appropriate interventions. To this end we compared the NEPSY-II profiles of 22 children with high-functioning autism spectrum disorders (HFASD) with those of 44 healthy control…

Disorder-induced losses in photonic crystal waveguides with line defects.

PubMed

Gerace, Dario; Andreani, Lucio Claudio

2004-08-15

A numerical analysis of extrinsic diffraction losses in two-dimensional photonic crystal slabs with line defects is reported. To model disorder, a Gaussian distribution of hole radii in the triangular lattice of airholes is assumed. The extrinsic losses below the light line increase quadratically with the disorder parameter, decrease slightly with increasing core thickness, and depend weakly on the hole radius. For typical values of the disorder parameter the calculated loss values of guided modes below the light line compare favorably with available experimental results.

Neuromuscular disorders in the intensive care unit.

PubMed

Marinelli, William A; Leatherman, James W

2002-10-01

Neuromuscular disorders encountered in the ICU can be categorized as muscular diseases that lead to ICU admission and those that are acquired in the ICU. This article discusses three neuromuscular disorders can lead to ICU admission and have a putative immune-mediated pathogenesis: the Guillian-Barré syndrome, myasthenia gravis, and dermatomyositis/polymyositis. It also reviews critical care polyneuropathy and ICU acquired myopathy, two disorders that, alone or in combination, are responsible for nearly all cases of severe ICU acquired muscle weakness.

Theory of current-driven skyrmions in disordered magnets.

PubMed

Koshibae, Wataru; Nagaosa, Naoto

2018-04-20

An emergent topological particle in magnets, skyrmion, has several unique features distinct from the other magnetic textures such as domain wall, helical structure, and vortex. It is characterized by a topological integer called skyrmion number N sk , which counts how many times the directions of the magnetic moments wrap the unit sphere. This N sk gives the chiral nature of the skyrmion dynamics, and leads to the extremely small critical current density j c for the current-driven motion in terms of spin transfer torque effect. The finite j c indicates the pinning effect due to the disorder such as impurities and defects, and the behaviors of skyrmions under disorder have not been explored well theoretically although it is always relevant in real systems. Here we reveal by a numerical simulation of Landau-Lifshitz-Gilbert equation that there are four different skyrmion phases with the strong disorder, i.e., (A) pinned state, (B) depinned state, (C) skyrmion multiplication/annihilation, and (D) segregation of skyrmions, as the current density increases, while only two phases (A) and (B) appear in the weak disorder case. The microscopic mechanisms of the new phases (C) and (D) are analyzed theoretically. These results offer a coherent understanding of the skyrmion dynamics under current with disorder.

Influence of lattice vibrations on the field driven electronic transport in chains with correlated disorder

NASA Astrophysics Data System (ADS)

da Silva, L. D.; Sales, M. O.; Ranciaro Neto, A.; Lyra, M. L.; de Moura, F. A. B. F.

2016-12-01

We investigate electronic transport in a one-dimensional model with four different types of atoms and long-ranged correlated disorder. The latter was attained by choosing an adequate distribution of on-site energies. The wave-packet dynamics is followed by taking into account effects due to a static electric field and electron-phonon coupling. In the absence of electron-phonon coupling, the competition between correlated disorder and the static electric field promotes the occurrence of wave-packet oscillations in the regime of strong correlations. When the electron-lattice coupling is switched on, phonon scattering degrades the Bloch oscillations. For weak electron-phonon couplings, a coherent oscillatory-like dynamics of the wave-packet centroid persists for short periods of time. For strong couplings the wave-packet acquires a diffusive-like displacement and spreading. A slower sub-diffusive spreading takes place in the regime of weak correlations.

Non-conventional Anderson localization in a matched quarter stack with metamaterials

NASA Astrophysics Data System (ADS)

Torres-Herrera, E. J.; Izrailev, F. M.; Makarov, N. M.

2013-05-01

We study the problem of non-conventional Anderson localization emerging in bilayer periodic-on-average structures with alternating layers of materials, with positive and negative refraction indices na and nb. Attention is paid to the model of the so-called quarter stack with perfectly matched layers (the same unperturbed by disorder impedances, Za = Zb, and optical path lengths, nada = |nb|db, with da and db being the thicknesses of basic layers). As was recently numerically discovered, in such structures with weak fluctuations of refractive indices (compositional disorder), the localization length Lloc is enormously large in comparison to the conventional localization occurring in the structures with positive refraction indices only. In this paper we develop a new approach, which allows us to derive the expression for Lloc for weak disorder and any wave frequency ω. In the limit ω → 0 one gets a quite specific dependence, L-1loc∝σ4ω8, which is obtained within the fourth order of perturbation theory. We also analyze the interplay between two types of disorder, when in addition to the fluctuations of na and nb, the thicknesses da and db slightly fluctuate as well (positional disorder). We show how conventional localization recovers with the addition of positional disorder.

Stigmatizing attitudes towards people with mental disorders: findings from an Australian National Survey of Mental Health Literacy and Stigma.

PubMed

Reavley, Nicola J; Jorm, Anthony F

2011-12-01

This paper reports findings from a national survey on stigmatizing attitudes towards people with depression, anxiety disorders and schizophrenia/psychosis. In 2011 telephone interviews were carried out with 6019 Australians aged 15 or over. Participants were presented with a case vignette describing either depression, depression with suicidal thoughts, early schizophrenia, chronic schizophrenia, social phobia or post-traumatic stress disorder. Questions were asked about stigmatizing attitudes, including perceptions of discrimination, personal and perceived stigma and desire for social distance. Chronic schizophrenia was most likely to be associated with dangerousness, unpredictability and a preference for not employing someone with the problem, while social phobia was most likely to be seen as due to personal weakness. Attitudes concerning dangerousness and social distance were greater in relation to men with mental disorders compared to women. Other people were perceived as more likely to hold stigmatizing attitudes than the respondents reported for themselves. Anti-stigma interventions are more likely to be successful if they focus on individual disorders rather than on 'mental illness' in general. Such interventions may need to address perceptions of social phobia as being due to weakness and those of dangerousness in people with more severe disorders. Such interventions should also focus on bringing beliefs about public perceptions in line with personal beliefs.

Coding of time-dependent stimuli in homogeneous and heterogeneous neural populations.

PubMed

Beiran, Manuel; Kruscha, Alexandra; Benda, Jan; Lindner, Benjamin

2018-04-01

We compare the information transmission of a time-dependent signal by two types of uncoupled neuron populations that differ in their sources of variability: i) a homogeneous population whose units receive independent noise and ii) a deterministic heterogeneous population, where each unit exhibits a different baseline firing rate ('disorder'). Our criterion for making both sources of variability quantitatively comparable is that the interspike-interval distributions are identical for both systems. Numerical simulations using leaky integrate-and-fire neurons unveil that a non-zero amount of both noise or disorder maximizes the encoding efficiency of the homogeneous and heterogeneous system, respectively, as a particular case of suprathreshold stochastic resonance. Our findings thus illustrate that heterogeneity can render similarly profitable effects for neuronal populations as dynamic noise. The optimal noise/disorder depends on the system size and the properties of the stimulus such as its intensity or cutoff frequency. We find that weak stimuli are better encoded by a noiseless heterogeneous population, whereas for strong stimuli a homogeneous population outperforms an equivalent heterogeneous system up to a moderate noise level. Furthermore, we derive analytical expressions of the coherence function for the cases of very strong noise and of vanishing intrinsic noise or heterogeneity, which predict the existence of an optimal noise intensity. Our results show that, depending on the type of signal, noise as well as heterogeneity can enhance the encoding performance of neuronal populations.

A recurrence network approach to analyzing forced synchronization in hydrodynamic systems

NASA Astrophysics Data System (ADS)

Murugesan, Meenatchidevi; Zhu, Yuanhang; Li, Larry K. B.

2016-11-01

Hydrodynamically self-excited systems can lock into external forcing, but their lock-in boundaries and the specific bifurcations through which they lock in can be difficult to detect. We propose using recurrence networks to analyze forced synchronization in a hydrodynamic system: a low-density jet. We find that as the jet bifurcates from periodicity (unforced) to quasiperiodicity (weak forcing) and then to lock-in (strong forcing), its recurrence network changes from a regular distribution of links between nodes (unforced) to a disordered topology (weak forcing) and then to a regular distribution again at lock-in (strong forcing). The emergence of order at lock-in can be either smooth or abrupt depending on the specific lock-in route taken. Furthermore, we find that before lock-in, the probability distribution of links in the network is a function of the characteristic scales of the system, which can be quantified with network measures and used to estimate the proximity to the lock-in boundaries. This study shows that recurrence networks can be used (i) to detect lock-in, (ii) to distinguish between different routes to lock-in, and (iii) as an early warning indicator of the proximity of a system to its lock-in boundaries. This work was supported by the Research Grants Council of Hong Kong (Project No. 16235716 and 26202815).

Does altering the occlusal vertical dimension produce temporomandibular disorders? A literature review.

PubMed

Moreno-Hay, I; Okeson, J P

2015-11-01

The purpose of this review was to present a comprehensive review of the scientific evidence available in the literature regarding the effect of altering the occlusal vertical dimens-ion (OVD) on producing temporomandibular disorders. The authors conducted a PubMed search with the following search terms 'temporoman-dibular disorders', 'occlusal vertical dimension', 'stomatognatic system', 'masticatory muscles' and 'skeletal muscle'. Bibliographies of all retrieved articles were consulted for additional publications. Hand-searched publications from 1938 were included. The literature review revealed a lack of well-designed studies. Traditional beliefs have been based on case reports and anecdotal opinions rather than on well-controlled clinical trials. The available evidence is weak and seems to indicate that the stomatognathic system has the ability to adapt rapidly to moderate changes in occlusal vertical dimension (OVD). Nevertheless, it should be taken into consideration that in some patients mild transient symptoms may occur, but they are most often self-limiting and without major consequence. In conclusion, there is no indication that permanent alteration in the OVD will produce long-lasting TMD symptoms. However, additional studies are needed. © 2015 John Wiley & Sons Ltd.

Rare regions and Griffiths singularities at a clean critical point: the five-dimensional disordered contact process.

PubMed

Vojta, Thomas; Igo, John; Hoyos, José A

2014-07-01

We investigate the nonequilibrium phase transition of the disordered contact process in five space dimensions by means of optimal fluctuation theory and Monte Carlo simulations. We find that the critical behavior is of mean-field type, i.e., identical to that of the clean five-dimensional contact process. It is accompanied by off-critical power-law Griffiths singularities whose dynamical exponent z' saturates at a finite value as the transition is approached. These findings resolve the apparent contradiction between the Harris criterion, which implies that weak disorder is renormalization-group irrelevant, and the rare-region classification, which predicts unconventional behavior. We confirm and illustrate our theory by large-scale Monte Carlo simulations of systems with up to 70(5) sites. We also relate our results to a recently established general relation between the Harris criterion and Griffiths singularities [Phys. Rev. Lett. 112, 075702 (2014)], and we discuss implications for other phase transitions.

Evidence of Reduced Global Processing in Autism Spectrum Disorder.

PubMed

Booth, Rhonda D L; Happé, Francesca G E

2018-04-01

Frith's original notion of 'weak central coherence' suggested that increased local processing in autism spectrum disorder (ASD) resulted from reduced global processing. More recent accounts have emphasised superior local perception and suggested intact global integration. However, tasks often place local and global processing in direct trade-off, making it difficult to determine whether group differences reflect reduced global processing, increased local processing, or both. We present two measures of global integration in which poor performance could not reflect increased local processing. ASD participants were slower to identify fragmented figures and less sensitive to global geometric impossibility than IQ-matched controls. These findings suggest that reduced global integration comprises one important facet of weak central coherence in ASD.

Anxiety sensitivity among Cambodian refugees with panic disorder: A factor analytic investigation.

PubMed

Hinton, Devon E; Pich, Vuth; Safren, Steven A; Pollack, Mark H; McNally, Richard J

2006-01-01

Among Cambodian refugees with panic disorder (N = 208), we performed two factor analyses, one with the ASI, another with an Augmented ASI (consisting of the 16-item ASI supplemented with a 9-item addendum that assesses additional Cambodian concerns about anxiety-related sensations). The principal component analysis of the ASI yielded a 3-factor solution (I, "Weak Heart Concerns"; II, "Social Concerns"; III, "Control Concerns"); the Augmented ASI, a 4-factor solution: I, "Wind Attack Concerns"; II, "Weak Heart Concerns"; III, "Social Concerns"; and IV, "Control Concerns." The item clustering within the factor solution of both the ASI and Augmented ASI illustrates the role of cultural syndromes in generating fear of mental and bodily events.

Paralysis as a Presenting Symptom of Hyperthyroidism in an Active Duty Soldier.

PubMed

Jennette, John; Tauferner, Dustin

2015-01-01

Thyrotoxic periodic paralysis (TPP) is an endocrine disorder presenting with proximal motor weakness, typically greatest in the lower extremities, hypokalemia, and signs or laboratory findings consistent with hyperthyroidism. The incidence of TPP is highest in Asian males. This is a case report of a 30-year-old male active duty Soldier who presented to the emergency department complaining of several recent episodes of lower extremity paralysis. The patient underwent a workup which included serum and cerebrospinal fluid studies, and was found to be hypokalemic and hyperthyroid. Following consultation with neurology, the patient was admitted to the medicine service and treated for thyrotoxic periodic paralysis with potassium replacement and treatment of his hyperthyroidism. Since achieving a euthyroid state, he has had no recurrences of TPP. This disease should be considered in patients presenting with symmetric motor weakness and hypokalemia, whether or not symptoms of hyperthyroidism are elicited during the review of systems.

The ICM research agenda on intensive care unit-acquired weakness.

PubMed

Latronico, Nicola; Herridge, Margaret; Hopkins, Ramona O; Angus, Derek; Hart, Nicholas; Hermans, Greet; Iwashyna, Theodore; Arabi, Yaseen; Citerio, Giuseppe; Wesley Ely, E; Hall, Jesse; Mehta, Sangeeta; Puntillo, Kathleen; Van den Hoeven, Johannes; Wunsch, Hannah; Cook, Deborah; Dos Santos, Claudia; Rubenfeld, Gordon; Vincent, Jean-Louis; Van den Berghe, Greet; Azoulay, Elie; Needham, Dale M

2017-09-01

We present areas of uncertainty concerning intensive care unit-acquired weakness (ICUAW) and identify areas for future research. Age, pre-ICU functional and cognitive state, concurrent illness, frailty, and health trajectories impact outcomes and should be assessed to stratify patients. In the ICU, early assessment of limb and diaphragm muscle strength and function using nonvolitional tests may be useful, but comparison with established methods of global and specific muscle strength and physical function and determination of their reliability and normal values would be important to advance these techniques. Serial measurements of limb and respiratory muscle strength, and systematic screening for dysphagia, would be helpful to clarify if and how weakness of these muscle groups is independently associated with outcome. ICUAW, delirium, and sedatives and analgesics may interact with each other, amplifying the effects of each individual factor. Reduced mobility in patients with hypoactive delirium needs investigations into dysfunction of central and peripheral nervous system motor pathways. Interventional nutritional studies should include muscle mass, strength, and physical function as outcomes, and prioritize elucidation of mechanisms. At follow-up, ICU survivors may suffer from prolonged muscle weakness and wasting and other physical impairments, as well as fatigue without demonstrable weakness on examination. Further studies should evaluate the prevalence and severity of fatigue in ICU survivors and define its association with psychiatric disorders, pain, cognitive impairment, and axonal loss. Finally, methodological issues, including accounting for baseline status, handling of missing data, and inclusion of patient-centered outcome measures should be addressed in future studies.

Thermal conductivity of nanocrystalline SiGe alloys using molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Abs da Cruz, Carolina; Katcho, Nebil A.; Mingo, Natalio; Veiga, Roberto G. A.

2013-10-01

We have studied the effect of nanocrystalline microstructure on the thermal conductivity of SiGe alloys using molecular dynamics simulations. Nanograins are modeled using both the coincidence site lattice and the Voronoi tessellation methods, and the thermal conductivity is computed using the Green-Kubo formalism. We analyze the dependence of the thermal conductivity with temperature, grain size L, and misorientation angle. We find a power dependence of L1/4 of the thermal conductivity with the grain size, instead of the linear dependence shown by non-alloyed nanograined systems. This dependence can be derived analytically underlines the important role that disorder scattering plays even when the grains are of the order of a few nm. This is in contrast to non-alloyed systems, where phonon transport is governed mainly by the boundary scattering. The temperature dependence is weak, in agreement with experimental measurements. The effect of angle misorientation is also small, which stresses the main role played by the disorder scattering.

Diaphragm Dysfunction in Critical Illness.

PubMed

Supinski, Gerald S; Morris, Peter E; Dhar, Sanjay; Callahan, Leigh Ann

2018-04-01

The diaphragm is the major muscle of inspiration, and its function is critical for optimal respiration. Diaphragmatic failure has long been recognized as a major contributor to death in a variety of systemic neuromuscular disorders. More recently, it is increasingly apparent that diaphragm dysfunction is present in a high percentage of critically ill patients and is associated with increased morbidity and mortality. In these patients, diaphragm weakness is thought to develop from disuse secondary to ventilator-induced diaphragm inactivity and as a consequence of the effects of systemic inflammation, including sepsis. This form of critical illness-acquired diaphragm dysfunction impairs the ability of the respiratory pump to compensate for an increased respiratory workload due to lung injury and fluid overload, leading to sustained respiratory failure and death. This review examines the presentation, causes, consequences, diagnosis, and treatment of disorders that result in acquired diaphragm dysfunction during critical illness. Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Cellular pathways of hereditary spastic paraplegia.

PubMed

Blackstone, Craig

2012-01-01

Human voluntary movement is controlled by the pyramidal motor system, a long CNS pathway comprising corticospinal and lower motor neurons. Hereditary spastic paraplegias (HSPs) are a large, genetically diverse group of inherited neurologic disorders characterized by a length-dependent distal axonopathy of the corticospinal tracts, resulting in lower limb spasticity and weakness. A range of studies are converging on alterations in the shaping of organelles, particularly the endoplasmic reticulum, as well as intracellular membrane trafficking and distribution as primary defects underlying the HSPs, with clear relevance for other long axonopathies affecting peripheral nerves and lower motor neurons.

Moessbauer effect: Study of disordered magnetic systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Xiao Sha.

1989-01-01

This dissertation describes Moessbauer spectroscopy studies of two chemically disordered binary, crystalline alloys having the composition A{sub 1-x}B{sub x}. Both systems are random 3d Heisenberg ferromagnets. In each case both A and B atoms carry a magnetic moment. The first study concerns a Moessbauer absorber experiment on Fe{sub 1-x} V{sub x}, in which the disorder in the critical region is of the annealed random exchange type. To eliminate the effect of concentration inhomogeneity, the measurement of the critical exponent {beta} was done on the alloy with x = 0.125, where dT{sub C}/dx = 0, yielding {beta} = 0.362(8) over themore » reduced temperature range 1.4 {times} 10{sup {minus}3} < t < 4.88 {times} 10{sup {minus}1}. This result confirms the theoretical prediction that the annealed disorder is irrelevant to critical behavior in this case. As expected the critical exponent {beta} is consistent with the expectation for the 3d Heisenberg model as well as the measured exponent of pure Fe. The second study involves a Moessbauer source experiment on {sup 57} CoPd{sub 0.80}Co{sub 0.20}, in which disorder is of the quenched random exchange type perturbed by a very weak random anisotropy interaction. The critical exponent {beta} deduced over the range 1 {times} 10{sup {minus}2} < t < 2 {times} 10{sup {minus}1} is 0.385(20), and is consistent with the theoretical prediction for quenched disordered 3d Heisenberg systems: the disorder is irrelevant to the critical behavior. However, because of the restricted range of reduced temperature, the result is insufficiently asymptotic to serve as a conclusive test of the theory. Outside the critical region the distribution of Fe{sup 57} hyperfine field in Pd{sub 0.80}Co{sub 0.20} is observed to have an anomalous temperature dependence characterized by a linear increase in the width of the field distribution for T/T{sub C} {ge} 0.6.« less

Validity of the Eating Attitudes Test and the Eating Disorders Inventory in Bulimia Nervosa.

ERIC Educational Resources Information Center

Gross, Janet; And Others

1986-01-01

Assessed criterion and concurrent validity of the Eating Attitudes Test and the Eating Disorder Inventory in 82 women with bulimia nervosa. Both tests demonstrated criterion validity by discriminating bulimia nervosa subjects from normals. Only weak support was found for concurrent validity within bulimia subjects. Recommends combination of…

Language Phenotypes and Intervention Planning: Bridging Research and Practice

ERIC Educational Resources Information Center

Fidler, Deborah J.; Philofsky, Amy; Hepburn, Susan L.

2007-01-01

This paper focuses on the communication and language phenotypes associated with three genetic disorders: Down syndrome, Williams syndrome, and fragile X syndrome. It is argued that there is empirical evidence that these disorders predispose children to specific profiles of strength and weakness in some areas of speech, language, and communication,…

Evidence for a Cultural Influence on Field-Independence in Autism Spectrum Disorder

ERIC Educational Resources Information Center

Koh, Hwan Cui; Milne, Elizabeth

2012-01-01

Field-independence, or weak central coherence, is a recognised phenotype of autism spectrum disorder (ASD). There is also evidence of cultural variation in this perceptual style, as neurotypical individuals from Western nations are more field-independent than neurotypical individuals from East-Asian nations. The majority of research on perceptual…

Acupuncture for Children with Autism Spectrum Disorders: A Systematic Review of Randomized Clinical Trials

ERIC Educational Resources Information Center

Lee, Myeong Soo; Choi, Tae-Young; Shin, Byung-Cheul; Ernst, Edzard

2012-01-01

This study aimed to assess the effectiveness of acupuncture as a treatment for autism spectrum disorders (ASD). We searched the literature using 15 databases. Eleven randomized clinical trials (RCTs) met our inclusion criteria. Most had significant methodological weaknesses. The studies' statistical and clinical heterogeneity prevented us from…

Multiple cognitive capabilities/deficits in children with an autism spectrum disorder: "weak" central coherence and its relationship to theory of mind and executive control.

PubMed

Pellicano, Elizabeth; Maybery, Murray; Durkin, Kevin; Maley, Alana

2006-01-01

This study examined the validity of "weak" central coherence (CC) in the context of multiple cognitive capabilities/deficits in autism. Children with an autism spectrum disorder (ASD) and matched typically developing children were administered tasks tapping visuospatial coherence, false-belief understanding and aspects of executive control. Significant group differences were found in all three cognitive domains. Evidence of local processing on coherence tasks was widespread in the ASD group, but difficulties in attributing false beliefs and in components of executive functioning were present in fewer of the children with ASD. This cognitive profile was generally similar for younger and older children with ASD. Furthermore, weak CC was unrelated to false-belief understanding, but aspects of coherence (related to integration) were associated with aspects of executive control. Few associations were found between cognitive variables and indices of autistic symptomatology. Implications for CC theory are discussed.

Neurocognitive performance of children with higher functioning autism spectrum disorders on the NEPSY-II.

PubMed

Barron-Linnankoski, Sarianna; Reinvall, Outi; Lahervuori, Anne; Voutilainen, Arja; Lahti-Nuuttila, Pekka; Korkman, Marit

2015-01-01

This study examined patterns of strengths and weaknesses in the neurocognitive performance of children with higher functioning autism spectrum disorder (ASD). The participants were 30 children with higher functioning ASD ranging from 6 to 11 years, and 60 typically developing (TD) children, who were matched with the children with higher functioning ASD in terms of age, gender, and maternal education. The TD children were drawn from the Finnish standardization sample for the NEPSY-II. The cognitive abilities of the children with higher functioning ASD were assessed with the WISC-III, and the neurocognitive performance of the children with higher functioning ASD and TD children on the NEPSY-II was compared. The children with higher functioning ASD were found to have strengths in verbal reasoning skills with respect to the population mean and weaknesses in set-shifting, verbal fluency, and narrative memory in comparison with the TD children. Minor weaknesses were also observed in facial memory and fine and visuomotor skills.

Transport in a disordered ν = 2 / 3 fractional quantum Hall junction

NASA Astrophysics Data System (ADS)

Protopopov, I. V.; Gefen, Yuval; Mirlin, A. D.

2017-10-01

Electric and thermal transport properties of a ν = 2 / 3 fractional quantum Hall junction are analyzed. We investigate the evolution of the electric and thermal two-terminal conductances, G and GQ, with system size L and temperature T. This is done both for the case of strong interaction between the 1 and 1/ 3 modes (when the low-temperature physics of the interacting segment of the device is controlled by the vicinity of the strong-disorder Kane-Fisher-Polchinski fixed point) and for relatively weak interaction, for which the disorder is irrelevant at T = 0 in the renormalization-group sense. The transport properties in both cases are similar in several respects. In particular, G(L) is close to 4/3 (in units of e2 / h) and GQ to 2 (in units of πT / 6 ħ) for small L, independently of the interaction strength. For large L the system is in an incoherent regime, with G given by 2/3 and GQ showing the Ohmic scaling, GQ ∝ 1 / L, again for any interaction strength. The hallmark of the strong-disorder fixed point is the emergence of an intermediate range of L, in which the electric conductance shows strong mesoscopic fluctuations and the thermal conductance is GQ = 1. The analysis is extended also to a device with floating 1/3 mode, as studied in a recent experiment (Grivnin et al. 2014).

Information processing in decision-making systems.

PubMed

van der Meer, Matthijs; Kurth-Nelson, Zeb; Redish, A David

2012-08-01

Decisions result from an interaction between multiple functional systems acting in parallel to process information in very different ways, each with strengths and weaknesses. In this review, the authors address three action-selection components of decision-making: The Pavlovian system releases an action from a limited repertoire of potential actions, such as approaching learned stimuli. Like the Pavlovian system, the habit system is computationally fast but, unlike the Pavlovian system permits arbitrary stimulus-action pairings. These associations are a "forward'' mechanism; when a situation is recognized, the action is released. In contrast, the deliberative system is flexible but takes time to process. The deliberative system uses knowledge of the causal structure of the world to search into the future, planning actions to maximize expected rewards. Deliberation depends on the ability to imagine future possibilities, including novel situations, and it allows decisions to be taken without having previously experienced the options. Various anatomical structures have been identified that carry out the information processing of each of these systems: hippocampus constitutes a map of the world that can be used for searching/imagining the future; dorsal striatal neurons represent situation-action associations; and ventral striatum maintains value representations for all three systems. Each system presents vulnerabilities to pathologies that can manifest as psychiatric disorders. Understanding these systems and their relation to neuroanatomy opens up a deeper way to treat the structural problems underlying various disorders.

Information Processing in Decision-Making Systems

PubMed Central

van der Meer, Matthijs; Kurth-Nelson, Zeb; Redish, A. David

2015-01-01

Decisions result from an interaction between multiple functional systems acting in parallel to process information in very different ways, each with strengths and weaknesses. In this review, the authors address three action-selection components of decision-making: The Pavlovian system releases an action from a limited repertoire of potential actions, such as approaching learned stimuli. Like the Pavlovian system, the habit system is computationally fast but, unlike the Pavlovian system permits arbitrary stimulus-action pairings. These associations are a “forward” mechanism; when a situation is recognized, the action is released. In contrast, the deliberative system is flexible but takes time to process. The deliberative system uses knowledge of the causal structure of the world to search into the future, planning actions to maximize expected rewards. Deliberation depends on the ability to imagine future possibilities, including novel situations, and it allows decisions to be taken without having previously experienced the options. Various anatomical structures have been identified that carry out the information processing of each of these systems: hippocampus constitutes a map of the world that can be used for searching/imagining the future; dorsal striatal neurons represent situation-action associations; and ventral striatum maintains value representations for all three systems. Each system presents vulnerabilities to pathologies that can manifest as psychiatric disorders. Understanding these systems and their relation to neuroanatomy opens up a deeper way to treat the structural problems underlying various disorders. PMID:22492194

Gender differences in diagnosing antisocial personality disorder in methadone patients.

PubMed

Rutherford, M J; Alterman, A I; Cacciola, J S; Snider, E C

1995-09-01

The goal of this study was to evaluate gender differences in the prevalence rates, short-term reliability, and internal consistency of the diagnosis of antisocial personality disorder for DSM-III-R, DSM-III, and Research Diagnostic Criteria (RDC). A total of 37 men and 57 women methadone patients were diagnosed according to DSM-III-R, DSM-III, and RDC antisocial personality disorder criteria. The diagnostic rates, reliability, and internal consistency were lower for women than for men in all systems. DSM-III criteria resulted in the highest reliability for women, but for men, the DSM-III criteria were the least reliable. Examination of endorsement rates of individual antisocial personality disorder criteria revealed several significant gender differences on the majority of childhood criteria and on several adult criteria. Item-total correlations revealed that for women, the violent and aggressive childhood criteria in DSM-III-R that had not been included in DSM-III or RDC had a negative or no correlation to the assessment of antisocial personality disorder for women. The change in DSM-III-R from DSM-III childhood criteria appears to have resulted in a decrease in internal consistency and rates of antisocial personality disorder for women, but not for men. The results of this investigation indicate that the psychometric properties of the current antisocial personality disorder scales are weak for women, compared with men. To assess antisocial personality disorder in women it may be necessary to revise current, or develop new, diagnostic criteria.

Theory of hydrodynamic transport in fluctuating electronic charge density wave states

NASA Astrophysics Data System (ADS)

Delacrétaz, Luca V.; Goutéraux, Blaise; Hartnoll, Sean A.; Karlsson, Anna

2017-11-01

We describe the collective hydrodynamic motion of an incommensurate charge density wave state in a clean electronic system. Our description simultaneously incorporates the effects of both pinning due to weak disorder and also phase relaxation due to proliferating dislocations. We show that the interplay between these two phenomena has important consequences for charge and momentum transport. For instance, it can lead to metal-insulator transitions. We furthermore identify signatures of fluctuating density waves in frequency and spatially resolved conductivities. Phase disordering is well known to lead to a large viscosity. We derive a precise formula for the phase relaxation rate in terms of the viscosity in the dislocation cores. We thereby determine the viscosity of the superconducting state of BSCCO from the observed melting dynamics of Abrikosov lattices and show that the result is consistent with dissipation into Bogoliubov quasiparticles.

The Influence of Hip Abductor Weakness on Frontal Plane Motion of the Trunk and Pelvis in Patients with Cerebral Palsy

ERIC Educational Resources Information Center

Krautwurst, Britta K.; Wolf, Sebastian I.; Heitzmann, Daniel W. W.; Gantz, Simone; Braatz, Frank; Dreher, Thomas

2013-01-01

Trendelenburg walking pattern is a common finding in various disorders, including cerebral palsy (CP), where it is seen in children and adults. Clinically, this deviation is viewed as a consequence of hip abductor weakness resulting in pelvic obliquity. Trunk lean to the ipsilateral side is a common compensatory mechanism to counteract pelvic…

Eating disorders in Austrian men: an intracultural and crosscultural comparison study.

PubMed

Mangweth, B; Pope, H G; Hudson, J I; Olivardia, R; Kinzl, J; Biebl, W

1997-01-01

We compared 30 male university students with eating disorders and 30 male comparison subjects without eating disorders recruited by advertisement at Innsbruck University, Austria. Subjects were interviewed using instruments that we had previously used in a controlled study of college men with eating disorders in the United States. The Austrian men with eating disorders differed sharply from Austrian comparison subjects, but closely resembled their American counterparts, on prevalence of personal and familial psychopathology, adverse family experiences, and scores on rating scales for eating disorder. Interestingly, dissatisfaction with body image was consistently greater among American subjects regardless of eating disorder status. Our data suggest a weak association between eating disorders and homosexual or bisexual orientation in men and no consistent association between eating disorders and childhood sexual abuse.

[Personality disorders, violence and criminal behaviour].

PubMed

Palmstierna, Tom

2016-12-06

Personality disorders, violence and criminal behaviour The importance of personality disorders for violent and criminal behaviour is illustrated by their high prevalence in prison populations. Especially antisocial personality disorder and antisocial personality traits are linked to violence. During diagnostic assessment of personality disorders, violence risk screening is recommended. Cognitive behaviour treatment focused on violent behaviour has some effect in criminal populations, but the antisocial personality traits are resistant to treatment. Evidence for pharmacological treatment of repetitive aggressive behaviour is weak. But, bensodiazepines seem to increase the risk of violent behaviour among patients with personality disorders. Antisocial personality traits diminish over time. This spontaneous decrease can be delayed by comorbidity such as other personality disorder, substance use disorder, psychosis and attention deficit disorders. Therefore it is recommended to actively treat these comorbid conditions.

Nature of the superconductor-insulator transition in disordered superconductors.

PubMed

Dubi, Yonatan; Meir, Yigal; Avishai, Yshai

2007-10-18

The interplay of superconductivity and disorder has intrigued scientists for several decades. Disorder is expected to enhance the electrical resistance of a system, whereas superconductivity is associated with a zero-resistance state. Although superconductivity has been predicted to persist even in the presence of disorder, experiments performed on thin films have demonstrated a transition from a superconducting to an insulating state with increasing disorder or magnetic field. The nature of this transition is still under debate, and the subject has become even more relevant with the realization that high-transition-temperature (high-T(c)) superconductors are intrinsically disordered. Here we present numerical simulations of the superconductor-insulator transition in two-dimensional disordered superconductors, starting from a microscopic description that includes thermal phase fluctuations. We demonstrate explicitly that disorder leads to the formation of islands where the superconducting order is high. For weak disorder, or high electron density, increasing the magnetic field results in the eventual vanishing of the amplitude of the superconducting order parameter, thereby forming an insulating state. On the other hand, at lower electron densities or higher disorder, increasing the magnetic field suppresses the correlations between the phases of the superconducting order parameter in different islands, giving rise to a different type of superconductor-insulator transition. One of the important predictions of this work is that in the regime of high disorder, there are still superconducting islands in the sample, even on the insulating side of the transition. This result, which is consistent with experiments, explains the recently observed huge magneto-resistance peak in disordered thin films and may be relevant to the observation of 'the pseudogap phenomenon' in underdoped high-T(c) superconductors.

Visual Processing in Adolescents with Autism Spectrum Disorder: Evidence from Embedded Figures and Configural Superiority Tests

ERIC Educational Resources Information Center

Dillen, Claudia; Steyaert, Jean; Op de Beeck, Hans P.; Boets, Bart

2015-01-01

The embedded figures test has often been used to reveal weak central coherence in individuals with autism spectrum disorder (ASD). Here, we administered a more standardized automated version of the embedded figures test in combination with the configural superiority task, to investigate the effect of contextual modulation on local feature…

A Weak Association between Traits of Attention-Deficit/Hyperactivity Disorder and Gambling in College Students

ERIC Educational Resources Information Center

Canu, Will H.; Schatz, Nicole K.

2011-01-01

Attention-Deficit/Hyperactivity Disorder (ADHD) has been characterized as a comorbidity to pathological gambling (PG). However, contradictory evidence has emerged, and it has not been established whether nonimpulsive features of ADHD (e.g., inattention, hyperactivity) contribute to PG risk, or how robust this relationship is in college samples.…

What Factors Place Children with Speech Sound Disorders at Risk for Reading Problems?

ERIC Educational Resources Information Center

Anthony, Jason L.; Aghara, Rachel Greenblatt; Dunkelberger, Martha J.; Anthony, Teresa I.; Williams, Jeffrey M.; Zhang, Zhou

2011-01-01

Purpose: To identify weaknesses in print awareness and phonological processing that place children with speech sound disorders (SSDs) at increased risk for reading difficulties. Method: Language, literacy, and phonological skills of 3 groups of preschool-age children were compared: a group of 68 children with SSDs, a group of 68 peers with normal…

Classification Agreement Analysis of Cross-Battery Assessment in the Identification of Specific Learning Disorders in Children and Youth

ERIC Educational Resources Information Center

Kranzler, John H.; Floyd, Randy G.; Benson, Nicholas; Zaboski, Brian; Thibodaux, Lia

2016-01-01

The Cross-Battery Assessment (XBA) approach to identifying a specific learning disorder (SLD) is based on the postulate that deficits in cognitive abilities in the presence of otherwise average general intelligence are causally related to academic achievement weaknesses. To examine this postulate, we conducted a classification agreement analysis…

Management of Child and Adolescent Eating Disorders: The Current Evidence Base and Future Directions

ERIC Educational Resources Information Center

Gowers, Simon; Bryant-Waugh, Rachel

2004-01-01

Although eating disorders in children and adolescents remain a serious cause of morbidity and mortality, the evidence base for effective interventions is surprisingly weak. The adult literature is growing steadily, but this is mainly with regard to psychological therapies for bulimia nervosa and to some extent in the field of pharmacotherapy. This…

Mathematical models of bipolar disorder

NASA Astrophysics Data System (ADS)

Daugherty, Darryl; Roque-Urrea, Tairi; Urrea-Roque, John; Troyer, Jessica; Wirkus, Stephen; Porter, Mason A.

2009-07-01

We use limit cycle oscillators to model bipolar II disorder, which is characterized by alternating hypomanic and depressive episodes and afflicts about 1% of the United States adult population. We consider two non-linear oscillator models of a single bipolar patient. In both frameworks, we begin with an untreated individual and examine the mathematical effects and resulting biological consequences of treatment. We also briefly consider the dynamics of interacting bipolar II individuals using weakly-coupled, weakly-damped harmonic oscillators. We discuss how the proposed models can be used as a framework for refined models that incorporate additional biological data. We conclude with a discussion of possible generalizations of our work, as there are several biologically-motivated extensions that can be readily incorporated into the series of models presented here.

Late onset GM2 gangliosidosis presenting with motor neuron disease: an autopsy case.

PubMed

Yokoyama, Teruo; Nakamura, Seigo; Horiuchi, Emiko; Ishiyama, Miyako; Kawashima, Rei; Nakamura, Kazuo; Hasegawa, Kazuko; Yagishita, Saburo

2014-06-01

Adult-onset GM2 gangliosidosis is very rare and only three autopsy cases have been reported up to now. We report herein an autopsy case of adult-onset GM2 gangliosidosis. The patient developed slowly progressive motor neuron disease-like symptoms after longstanding mood disorder and cognitive dysfunction. He developed gait disturbance and weakness of lower limbs at age 52 years. Because of progressive muscle weakness and atrophy, he became bed-ridden at age 65. At age of 68, he died. His neurological findings presented slight cognitive disturbance, slight manic state, severe muscle weakness, atrophy of four limbs and no extrapyramidal signs and symptoms, and cerebellar ataxia. Neuropathologically, mild neuronal loss and abundant lipid deposits were noted in the neuronal cytoplasm throughout the nervous system, including peripheral autonomic neurons. The most outstanding findings were marked neuronal loss and distended neurons in the anterior horn of the spinal cord, which supports his clinical symptomatology of lower motor neuron disease in this case. The presence of lipofuscin, zebra bodies and membranous cytoplasmic bodies (MCB) and the increase of GM2 ganglioside by biochemistry led to diagnosis of GM2 gangliosidosis. © 2013 Japanese Society of Neuropathology.

Symptom-specific self-referential cognitive processes in bipolar disorder: a longitudinal analysis.

PubMed

Pavlickova, H; Varese, F; Turnbull, O; Scott, J; Morriss, R; Kinderman, P; Paykel, E; Bentall, R P

2013-09-01

Although depression and mania are often assumed to be polar opposites, studies have shown that, in patients with bipolar disorder, they are weakly positively correlated and vary somewhat independently over time. Thus, when investigating relationships between specific psychological processes and specific symptoms (mania and depression), co-morbidity between the symptoms and changes over time must be taken into account. Method A total of 253 bipolar disorder patients were assessed every 24 weeks for 18 months using the Hamilton Rating Scale for Depression (HAMD), the Bech-Rafaelsen Mania Assessment Scale (MAS), the Rosenberg Self-Esteem Questionnaire (RSEQ), the Dysfunctional Attitudes Scale (DAS), the Internal, Personal and Situational Attributions Questionnaire (IPSAQ) and the Personal Qualities Questionnaire (PQQ). We calculated multilevel models using the xtreg module of Stata 9.1, with psychological and clinical measures nested within each participant. Mania and depression were weakly, yet significantly, associated; each was related to distinct psychological processes. Cross-sectionally, self-esteem showed the most robust associations with depression and mania: depression was associated with low positive and high negative self-esteem, and mania with high positive self-esteem. Depression was significantly associated with most of the other self-referential measures, whereas mania was weakly associated only with the externalizing bias of the IPSAQ and the achievement scale of the DAS. Prospectively, low self-esteem predicted future depression. The associations between different self-referential thinking processes and different phases of bipolar disorder, and the presence of the negative self-concept in both depression and mania, have implications for therapeutic management, and also for future directions of research.

Hurst revisited: Are symptoms and signs of functional motor and sensory disorders "dependent on idea"?

PubMed

Stone, Jon; Mutch, Jennifer; Giannokous, Denis; Hoeritzauer, Ingrid; Carson, Alan

2017-10-15

Symptoms and signs of functional (psychogenic) motor and sensory disorder are often said to be dependent on the patients' idea of what symptoms should be, rather than anatomy and physiology. This hypothesis has however rarely been tested. Inspired by a brief experiment carried out in 1919 by neurologist Arthur Hurst we aimed to assess the views of healthy non-medical adults towards paralysis and numbness and their response to tests for functional disorders when asked to pretend to have motor and sensory symptoms. When subjects were asked to pretend they had a paralysed arm 80% thought there would be sensory loss. Of these 60% thought it would have a circumferential (functional) distribution at the wrist, elbow or shoulder. Hoover's sign of functional weakness was only positive in 75% of patients pretending to have leg paralysis with 23% maintaining weakness of hip extension in the feigned weak leg, a rare finding in neurological practice. 20% of subjects managed to continue having their feigned tremor during the entrainment test. 52% of subjects thought there was asymmetry of a tuning fork across their forehead even when no prior instruction had been given. The study confirmed Hurst's finding that non-medical people generally expect sensory loss to go along with paralysis, especially if the examiner suggests it. When present, it usually conforms to functional patterns of sensory loss. Clinical tests for functional and motor disorders appear to behave somewhat differently in patients asked to pretend to have symptoms suggesting that larger more detailed studies would be worthwhile. Copyright © 2017 Elsevier B.V. All rights reserved.

Recommendations for acupuncture in clinical practice guidelines of the national guideline clearinghouse.

PubMed

Guo, Yao; Zhao, Hong; Wang, Fang; Li, Si-Nuo; Sun, Yu-Xiu; Han, Ming-Juan; Liu, Bao-Yan

2017-11-01

To organize the clinical practice guidelines (CPGs) related to acupuncture included in the National Guideline Clearinghouse (NGC) to systematically summarize the diseases and disorders most commonly treated with acupuncture, the strength of recommendations for acupuncture and the quality of evidence. The NGC database was systematically searched for guidelines that included acupuncture as an intervention. Two independent reviewers studied the summaries and the full texts of the guidelines and included guidelines based on the inclusion and exclusion criteria. Thirty-nine guidelines were collected with 80 recommendations. The Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument was used to assess the quality of these guidelines. Of the 80 recommendations on acupuncture, 49 recommendations were clearly for acupuncture, 25 recommendations were against acupuncture and 6 recommendations did not indicate any clear recommendations, 37 recommendations were for painful diseases/disorders, and 12 recommendations were for non-painful diseases/disorders. Locomotor system disorders were the most common in the painful diseases/disorders category. Out of all the recommendations for acupuncture, most recommendations (87.76%) were weak in strength, and most of the evidence (40.84%) was of low quality. In the National Guideline Clearinghouse, the recommendations for acupuncture focus on painful diseases/disorders. The recommendations in the guidelines are not high in strength, and most of the evidence is moderate or low in quality.

A Few Close Friends: The Pediatrician's Role in the Management of Social Skills Deficits in Adolescent Children.

PubMed

Braddock, Barbara A; Twyman, Kimberly A; Garrity, Matthew R; Wang, Tracy; Neary, Meaghan K; Ezzelgot, Jamie; Heithaus, Jennifer L

2015-10-01

Pediatricians must recognize and respond to adolescents with social skills deficits because they are at heightened risk for mental health disorders, peer victimization, and social isolation. The aim of this project was to describe a group of adolescent children at the time of enrollment into social skills treatment. Ninety participants with neurodevelopmental weaknesses or disorders, to include high-functioning autism spectrum disorder, participated. Results showed that adolescents referred for social skills deficits had communication weaknesses and concerns in everyday social reciprocal behavior. They rarely hosted get-togethers with same-aged peers and were not often invited by same-aged peers to get-togethers. Twenty-nine percent of participants reported that they were victims of bullying, and more than half of participants reported clinically significant ostracism experiences. Results are discussed in terms of the pediatrician's role in the prevention, identification, and treatment of social skills deficits in light of recent research showing brain neuroplasticity extending into adolescence. © The Author(s) 2015.

Attention deficit hyperactivity disorder symptoms reporting in Malaysian adolescents: do adolescents, parents and teachers agree with each other?

PubMed

Wan Salwina, Wan Ismail; Baharudin, Azlin; Nik Ruzyanei, Nik Jaafar; Midin, Marhani; Rahman, Fairuz Nazri Abdul

2013-12-01

Attention Deficit Hyperactivity Disorder (ADHD) is a clinical diagnosis relying on persistence of symptoms across different settings. Information are gathered from different informants including adolescents, parents and teachers. In this cross-sectional study involving 410 twelve-year old adolescents, 37 teachers and 367 parents from seven schools in the Federal Territory of Kuala Lumpur, reliability of ADHD symptoms among the various informants were reported. ADHD symptoms (i.e. predominantly hyperactive, predominantly inattentive and combined symptoms) were assessed by adolescents, teachers and parents, using Conners-Wells' Adolescent Self-report Scale (CASS), Conner's Teachers Rating Scale (CTRS) and Conner's Parents Rating Scale (CPRS) respectively. For predominantly hyperactive symptoms, there were statistically significant, weak positive correlations between parents and teachers reporting (r=0.241, p<0.01). Statistically significant, weak positive correlations were found between adolescents and parents for predominantly inattentive symptoms (r=0.283, p<0.01). Correlations between adolescents and parents reporting were statistically significant but weak (r=0.294, p<0.01). Weak correlations exist between the different informants reporting ADHD symptoms among Malaysian adolescents. While multiple informant ratings are required to facilitate the diagnosis of ADHD, effort should be taken to minimize the disagreement in reporting and better utilize the information. Copyright © 2013 Elsevier B.V. All rights reserved.

Comorbidity between reading disability and math disability: concurrent psychopathology, functional impairment, and neuropsychological functioning.

PubMed

Willcutt, Erik G; Petrill, Stephen A; Wu, Sarah; Boada, Richard; Defries, John C; Olson, Richard K; Pennington, Bruce F

2013-01-01

Reading disability (RD) and math disability (MD) frequently co-occur, but the etiology of this comorbidity is not well understood. Groups with RD only (N = 241), MD only (N = 183), and RD + MD (N = 188) and a control group with neither disorder (N = 411) completed a battery of measures of internalizing and externalizing psychopathology, social and academic functioning, and 10 neuropsychological processes. Groups with RD only, MD only, and RD + MD were significantly impaired versus the control group on nearly all measures, and the group with RD + MD was more impaired than the groups with MD and RD alone on measures of internalizing psychopathology, academic functioning, and 7 of 10 neuropsychological constructs. Multiple regression analyses of the neuropsychological measures indicated that deficits in reading and math were associated with shared weaknesses in working memory, processing speed, and verbal comprehension. In contrast, reading difficulties were uniquely associated with weaknesses in phoneme awareness and naming speed, and math deficits were uniquely associated with weaknesses in set shifting. These results support multiple-deficit neuropsychological models of RD and MD and suggest that RD and MD are distinct but related disorders that co-occur because of shared neuropsychological weaknesses in working memory, processing speed, and verbal comprehension.

Systemic Lupus Erythematosus and Sjögren's Syndrome Complicated by Conversion Disorder: a Case Report.

PubMed

Nakamura, Misa; Tanaka, Seiji; Inoue, Tadashi; Maeda, Yasuto; Okumiya, Kiyohito; Esaki, Takuya; Shimomura, G O; Masunaga, Kenji; Nagamitsu, Shinichiro; Yamashita, Yushiro

2018-05-21

Conversion disorder (CD) is sometimes accompanied by motor and sensory impairments, such as muscle weakness, paralysis, sensory hypersensitivity, and sensory loss. Sjögren's syndrome (SS) complicates 5-10% of cases of systemic lupus erythematosus (SLE). Patients with SS or SLE present with various neurological symptoms and psychiatric manifestations. When neurological symptoms are present, it is important to distinguish whether the symptoms are caused by a neurological or a mental disorder because the former requires early intensive intervention, such as methylprednisolone pulse therapy (MPT), whereas psychotherapy or antidepressant drugs are recommended for mental disorders. We noticed SS- and SLE-like symptoms just after a diagnosis of idiopathic thrombocytopenic purpura in a 14-year-old girl. At approximately the same time, paralysis started in her lower limbs and subsequently spread to her upper limbs. An examination for neurological symptoms revealed no abnormalities. Because of the conversion reaction between her neurological symptoms and her disease state, CD was suspected as the etiology of her physical symptoms. Nevertheless, because of the progressive nature of the neurological symptoms, MPT was initiated with concurrent administration of intravenous immunoglobulin, but it failed to achieve a good outcome. The patient's symptoms eventually improved after she underwent psychotherapy treatment for a few months. Because early diagnosis of the cause of neurological symptoms accompanying SS and SLE is difficult, it may be necessary to combine the two lines of treatment in the early stages. However, when a mental disorder is suspected, psychotherapy should be started early to minimize the use of unnecessary neurological treatment.

Aquatic rehabilitation for the treatment of neurological disorders.

PubMed

Morris, D M

1994-01-01

Patients with neurological disorders present therapists with complex challenges for treatment, including weakness, hypertonicity, voluntary movement deficit, limited range of motion, sensory loss, incoordination, and postural instability. The presence of one or more of these impairments negatively influences these patients by contributing to problems in walking, transferring, and reaching. Aquatic rehabilitation offers a unique, versatile approach to the treatment of these disabilities. This article examines the problems encountered by patients with neurological disorders, general principles guiding neurotreatment, and aquatic neurorehabilitation approaches.

Profiles of executive function in parents and siblings of individuals with autism spectrum disorders.

PubMed

Wong, D; Maybery, M; Bishop, D V M; Maley, A; Hallmayer, J

2006-11-01

Delineation of a cognitive endophenotype for autism is useful both for exploring the genetic mechanisms underlying the disorder and for identifying which cognitive traits may be primary to it. This study investigated whether first-degree relatives of individuals with autism spectrum disorders (ASDs) demonstrate a specific profile of performance on a range of components of executive function (EF), to determine whether EF deficits represent possible endophenotypes for autism. Parents and siblings of ASD and control probands were tested on EF tasks measuring planning, set-shifting, inhibition and generativity. ASD parents showed poorer performance than control parents on a test of ideational fluency or generativity, and ASD fathers demonstrated a weakness in set-shifting to a previously irrelevant dimension. ASD siblings revealed a mild reduction in ideational fluency and a weakness in non-verbal generativity when compared with control siblings. Neither ASD parents nor siblings displayed significant difficulties with planning or inhibition. These results indicated that the broad autism phenotype may not be characterized primarily by impairments in planning and cognitive flexibility, as had been previously proposed. Weaknesses in generativity emerged as stronger potential endophenotypes in this study, suggesting that this aspect of EF should play a central role in cognitive theories of autism. However, discrepancies in the EF profile demonstrated by parents and siblings suggest that factors related to age or parental responsibility may affect the precise pattern of deficits observed.

The Effect of Rehearsal Training on Working Memory Span of Children with Fetal Alcohol Spectrum Disorder

ERIC Educational Resources Information Center

Loomes, Carly; Rasmussen, Carmen; Pei, Jacqueline; Manji, Shazeen; Andrew, Gail

2008-01-01

A key area of weakness in individuals with fetal alcohol spectrum disorder (FASD) is working memory, thus the goal of this study was to determine whether teaching children (aged 4-11) with FASD verbal rehearsal would increase their memory. Rehearsal training has been effective in other populations with working memory difficulties, so we…

Developmental Co-Ordination Disorder (DCD) in Adolescents and Adults in Further and Higher Education

ERIC Educational Resources Information Center

Kirby, Amanda; Sugden, David; Beveridge, Sally; Edwards, Lisa

2008-01-01

Few studies have looked at the strengths and weaknesses and needs of students with developmental co-ordination disorder (DCD). This paper describes a cohort of 93 UK students currently studying at further or higher education and who have reported motor difficulties present since childhood. The study group consisted of 21 reporting to have DCD…

Translational science and the hidden research system in universities and academic hospitals: a case study.

PubMed

Lander, Bryn; Atkinson-Grosjean, Janet

2011-02-01

Innovation systems (IS) and science policy scholarship predominantly focus on linkages between universities and industry, and the commercial translation of academic discoveries. Overlooked in such analyses are important connections between universities and academic hospitals, and the non-commercial aspects of translational science. The two types of institutions tend to be collapsed into a single entity-'the university'-and relational flows are lost. Yet the distinctions and flows between the two are crucial elements of translational science and the biomedical innovation system. This paper explores what has been called the 'hidden research system' that connects hospitals, universities, and their resources, with the clinical and scientific actors who make the linkages possible. Then, using a novel conceptual model of translational science, we examine the individual interactions and dynamics involved in a particular example of the biomedical innovation system at work: the diagnosis of IRAK-4 deficiency, a rare immunological disorder, and the translational flows that result. Contra to conventional IS analyses, we are able to point to the strong role of public-sector institutions, and the weak role of the private-sector, in the translational processes described here. Our research was conducted within a Canadian network of scientists and clinician-scientists studying the pathogenomics of immunological disorders and innate immunity. Copyright © 2010 Elsevier Ltd. All rights reserved.

Non-neural Muscle Weakness Has Limited Influence on Complexity of Motor Control during Gait

PubMed Central

Goudriaan, Marije; Shuman, Benjamin R.; Steele, Katherine M.; Van den Hauwe, Marleen; Goemans, Nathalie; Molenaers, Guy; Desloovere, Kaat

2018-01-01

Cerebral palsy (CP) and Duchenne muscular dystrophy (DMD) are neuromuscular disorders characterized by muscle weakness. Weakness in CP has neural and non-neural components, whereas in DMD, weakness can be considered as a predominantly non-neural problem. Despite the different underlying causes, weakness is a constraint for the central nervous system when controlling gait. CP demonstrates decreased complexity of motor control during gait from muscle synergy analysis, which is reflected by a higher total variance accounted for by one synergy (tVAF1). However, it remains unclear if weakness directly contributes to higher tVAF1 in CP, or whether altered tVAF1 reflects mainly neural impairments. If muscle weakness directly contributes to higher tVAF1, then tVAF1 should also be increased in DMD. To examine the etiology of increased tVAF1, muscle activity data of gluteus medius, rectus femoris, medial hamstrings, medial gastrocnemius, and tibialis anterior were measured at self-selected walking speed, and strength data from knee extensors, knee flexors, dorsiflexors and plantar flexors, were analyzed in 15 children with CP [median (IQR) age: 8.9 (2.2)], 15 boys with DMD [8.7 (3.1)], and 15 typical developing (TD) children [8.6 (2.7)]. We computed tVAF1 from 10 concatenated steps with non-negative matrix factorization, and compared tVAF1 between the three groups with a Mann-Whiney U-test. Spearman's rank correlation coefficients were used to determine if weakness in specific muscle groups contributed to altered tVAF1. No significant differences in tVAF1 were found between DMD [tVAF1: 0.60 (0.07)] and TD children [0.65 (0.07)], while tVAF1 was significantly higher in CP [(0.74 (0.09)] than in the other groups (both p < 0.005). In CP, weakness in the plantar flexors was related to higher tVAF1 (r = −0.72). In DMD, knee extensor weakness related to increased tVAF1 (r = −0.50). These results suggest that the non-neural weakness in DMD had limited influence on complexity of motor control during gait and that the higher tVAF1 in children with CP is mainly related to neural impairments caused by the brain lesion. PMID:29445330

BAG3 myofibrillar myopathy presenting with cardiomyopathy.

PubMed

Konersman, Chamindra G; Bordini, Brett J; Scharer, Gunter; Lawlor, Michael W; Zangwill, Steven; Southern, James F; Amos, Louella; Geddes, Gabrielle C; Kliegman, Robert; Collins, Michael P

2015-05-01

Myofibrillar myopathies (MFMs) are a heterogeneous group of neuromuscular disorders distinguished by the pathological hallmark of myofibrillar dissolution. Most patients present in adulthood, but mutations in several genes including BCL2-associated athanogene 3 (BAG3) cause predominantly childhood-onset disease. BAG3-related MFM is particularly severe, featuring weakness, cardiomyopathy, neuropathy, and early lethality. While prior cases reported either neuromuscular weakness or concurrent weakness and cardiomyopathy at onset, we describe the first case in which cardiomyopathy and cardiac transplantation (age eight) preceded neuromuscular weakness by several years (age 12). The phenotype comprised distal weakness and severe sensorimotor neuropathy. Nerve biopsy was primarily axonal with secondary demyelinating/remyelinating changes without "giant axons." Muscle biopsy showed extensive neuropathic changes that made myopathic changes difficult to interpret. Similar to previous cases, a p.Pro209Leu mutation in exon 3 of BAG3 was found. This case underlines the importance of evaluating for MFMs in patients with combined neuromuscular weakness and cardiomyopathy. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of DSM-IV-TR and DSM-5 Criteria in Diagnosing Autism Spectrum Disorders in Singapore.

PubMed

Sung, Min; Goh, Tze Jui; Tan, Bei Lin Joelene; Chan, Jialei Stephanie; Liew, Hwee Sen Alvin

2018-04-28

Our study examines the Diagnostic and Statistical Manual-Fifth Edition (DSM-5) and Diagnostic and Statistical Manual-Fourth Edition, Text Revision (DSM-IV-TR) when applied concurrently against the best estimate clinical diagnoses for 110 children (5.1-19.6 years old) referred for diagnostic assessments of Autism Spectrum Disorder (ASD) in a Singaporean outpatient speciality clinic. DSM-IV-TR performed slightly better, yielding sensitivity of 0.946 and specificity of 0.889, compared to DSM-5 (sensitivity = 0.837; specificity = 0.833). When considering the ASD sub-categories, sensitivity ranged from 0.667 to 0.933, and specificity ranged from 0.900 to 0.975. More participants with a PDD-NOS best estimate clinical diagnosis (40%) were misclassified on DSM-5. Merits and weaknesses to both classification systems, and implications for access to services and policy changes are discussed.

Modelling Errors in Automatic Speech Recognition for Dysarthric Speakers

NASA Astrophysics Data System (ADS)

Caballero Morales, Santiago Omar; Cox, Stephen J.

2009-12-01

Dysarthria is a motor speech disorder characterized by weakness, paralysis, or poor coordination of the muscles responsible for speech. Although automatic speech recognition (ASR) systems have been developed for disordered speech, factors such as low intelligibility and limited phonemic repertoire decrease speech recognition accuracy, making conventional speaker adaptation algorithms perform poorly on dysarthric speakers. In this work, rather than adapting the acoustic models, we model the errors made by the speaker and attempt to correct them. For this task, two techniques have been developed: (1) a set of "metamodels" that incorporate a model of the speaker's phonetic confusion matrix into the ASR process; (2) a cascade of weighted finite-state transducers at the confusion matrix, word, and language levels. Both techniques attempt to correct the errors made at the phonetic level and make use of a language model to find the best estimate of the correct word sequence. Our experiments show that both techniques outperform standard adaptation techniques.

The neurofibromatoses. Part 2: NF2 and schwannomatosis.

PubMed

Lu-Emerson, Christine; Plotkin, Scott R

2009-01-01

The neurofibromatoses, including neurofibromatosis 1 (NF1), neurofibromatosis 2 (NF2), and schwannomatosis, comprise a group of genetically distinct disorders of the nervous system that are unified by the predisposition to nerve sheath tumors. All 3 types of NF have tumor manifestations (consistent with tumor-suppressor status) and nontumor manifestations. In the second part of this 2-part series, the manifestations of NF2 and schwannomatosis are reviewed. NF2 is characterized by bilateral vestibular schwannomas, meningiomas, ependymomas, cataracts, and epiretinal membranes. The combination of complete hearing loss from vestibular schwannomas and blindness from bifacial weakness is a devastating potential outcome of NF2. Schwannomatosis is characterized by multiple nonvestibular, nonintradermal schwannomas and chronic pain. Recently, germline alterations in the SMARCB1/INI1 gene have been implicated in both familial and sporadic forms of this disorder. Neurologists play an important role in the diagnosis and management of the neurofibromatoses.

Ca2+ sensitizers: An emerging class of agents for counterbalancing weakness in skeletal muscle diseases?

PubMed

Ochala, Julien

2010-02-01

Ca(2+) ions are key regulators of skeletal muscle contraction. By binding to contractile proteins, they initiate a cascade of molecular events leading to cross-bridge formation and ultimately, muscle shortening and force production. The ability of contractile proteins to respond to Ca(2+) attachment, also known as Ca(2+) sensitivity, is often compromised in acquired and congenital skeletal muscle disorders. It constitutes, undoubtedly, a major physiological cause of weakness for patients. In this review, we discuss recent studies giving strong molecular and cellular evidence that pharmacological modulators of some of the contractile proteins, also termed Ca(2+) sensitizers, are efficient agents to improve Ca(2+) sensitivity and function in diseased skeletal muscle cells. In fact, they compensate for the impaired contractile proteins response to Ca(2+) binding. Currently, such Ca(2+) sensitizing compounds are successfully used for reducing problems in cardiac disorders. Therefore, in the future, under certain conditions, these agents may represent an emerging class of agents to enhance the quality of life of patients suffering from skeletal muscle weakness. Copyright 2009 Elsevier B.V. All rights reserved.

Evidence for a cultural influence on field-independence in autism spectrum disorder.

PubMed

Koh, Hwan Cui; Milne, Elizabeth

2012-02-01

Field-independence, or weak central coherence, is a recognised phenotype of autism spectrum disorder (ASD). There is also evidence of cultural variation in this perceptual style, as neurotypical individuals from Western nations are more field-independent than neurotypical individuals from East-Asian nations. The majority of research on perceptual style in those with ASD has been carried out in Western nations therefore it is unclear whether increased field-independence in ASD is a culturally universal phenotype. Here, we assessed perceptual style in children with and without ASD from England and Singapore using the Children's Embedded Figures Test and the Framed-Line Test. We found increased field-independence in the English participants with ASD only, suggesting that weak central coherence in ASD is not culturally universal.

Receptive Vocabulary in Boys with Autism Spectrum Disorder: Cross-Sectional Developmental Trajectories

PubMed Central

McDuffie, Andrea S.; Hagerman, Randi J.; Abbeduto, Leonard

2013-01-01

In light of evidence that receptive language may be a relative weakness for individuals with autism spectrum disorder (ASD), this study characterized receptive vocabulary profiles in boys with ASD using cross-sectional developmental trajectories relative to age, nonverbal cognition, and expressive vocabulary. Participants were 49 boys with ASD (4–11 years) and 80 typically developing boys (2–11 years). Receptive vocabulary, assessed with the Peabody Picture Vocabulary Test, was a weakness for boys with ASD relative to age and nonverbal cognition. Relative to expressive vocabulary, assessed with the Expressive Vocabulary Test, receptive vocabulary increased at a lower rate for boys with ASD. Vocabulary trajectories in ASD are distinguished from typical development; however, nonverbal cognition largely accounts for the patterns observed. PMID:23588510

Conductivity of Weakly Disordered Metals Close to a "Ferromagnetic" Quantum Critical Point

NASA Astrophysics Data System (ADS)

Kastrinakis, George

2018-05-01

We calculate analytically the conductivity of weakly disordered metals close to a "ferromagnetic" quantum critical point in the low-temperature regime. Ferromagnetic in the sense that the effective carrier potential V(q,ω ), due to critical fluctuations, is peaked at zero momentum q=0. Vertex corrections, due to both critical fluctuations and impurity scattering, are explicitly considered. We find that only the vertex corrections due to impurity scattering, combined with the self-energy, generate appreciable effects as a function of the temperature T and the control parameter a, which measures the proximity to the critical point. Our results are consistent with resistivity experiments in several materials displaying typical Fermi liquid behaviour, but with a diverging prefactor of the T^2 term for small a.

Protecting clean critical points by local disorder correlations

NASA Astrophysics Data System (ADS)

Hoyos, J. A.; Laflorencie, Nicolas; Vieira, André.; Vojta, Thomas

2011-03-01

We show that a broad class of quantum critical points can be stable against locally correlated disorder even if they are unstable against uncorrelated disorder. Although this result seemingly contradicts the Harris criterion, it follows naturally from the absence of a random-mass term in the associated order-parameter field theory. We illustrate the general concept with explicit calculations for quantum spin-chain models. Instead of the infinite-randomness physics induced by uncorrelated disorder, we find that weak locally correlated disorder is irrelevant. For larger disorder, we find a line of critical points with unusual properties such as an increase of the entanglement entropy with the disorder strength. We also propose experimental realizations in the context of quantum magnetism and cold-atom physics. Financial support: Fapesp, CNPq, NSF, and Research Corporation.

Prospective Investigation of Video Game Use in Children and Subsequent Conduct Disorder and Depression Using Data from the Avon Longitudinal Study of Parents and Children

PubMed Central

Rutherford, Adam D.; Munafò, Marcus R.

2016-01-01

There is increasing public and scientific concern regarding the long-term behavioural effects of video game use in children, but currently little consensus as to the nature of any such relationships. We investigated the relationship between video game use in children, degree of violence in games, and measures of depression and a 6-level banded measure of conduct disorder. Data from the Avon Longitudinal Study of Parents and Children were used. A 3-level measure of game use at age 8/9 years was developed, taking into account degree of violence based on game genre. Associations with conduct disorder and depression, measured at age 15, were investigated using ordinal logistic regression, adjusted for a number of potential confounders. Shoot-em-up games were associated with conduct disorder bands, and with a binary measure of conduct disorder, although the strength of evidence for these associations was weak. A sensitivity analysis comparing those who play competitive games to those who play shoot-em-ups found weak evidence supporting the hypothesis that it is violence rather than competitiveness that is associated with conduct disorder. However this analysis was underpowered, and we cannot rule out the possibility that increasing levels of competition in games may be just as likely to account for the observed associations as violent content. Overall game exposure as indicated by number of games in a household was not related to conduct disorder, nor was any association found between shoot-em-up video game use and depression. PMID:26820149

Prospective Investigation of Video Game Use in Children and Subsequent Conduct Disorder and Depression Using Data from the Avon Longitudinal Study of Parents and Children.

PubMed

Etchells, Peter J; Gage, Suzanne H; Rutherford, Adam D; Munafò, Marcus R

2016-01-01

There is increasing public and scientific concern regarding the long-term behavioural effects of video game use in children, but currently little consensus as to the nature of any such relationships. We investigated the relationship between video game use in children, degree of violence in games, and measures of depression and a 6-level banded measure of conduct disorder. Data from the Avon Longitudinal Study of Parents and Children were used. A 3-level measure of game use at age 8/9 years was developed, taking into account degree of violence based on game genre. Associations with conduct disorder and depression, measured at age 15, were investigated using ordinal logistic regression, adjusted for a number of potential confounders. Shoot-em-up games were associated with conduct disorder bands, and with a binary measure of conduct disorder, although the strength of evidence for these associations was weak. A sensitivity analysis comparing those who play competitive games to those who play shoot-em-ups found weak evidence supporting the hypothesis that it is violence rather than competitiveness that is associated with conduct disorder. However this analysis was underpowered, and we cannot rule out the possibility that increasing levels of competition in games may be just as likely to account for the observed associations as violent content. Overall game exposure as indicated by number of games in a household was not related to conduct disorder, nor was any association found between shoot-em-up video game use and depression.

Working memory deficits in high-functioning adolescents with autism spectrum disorders: neuropsychological and neuroimaging correlates.

PubMed

Barendse, Evelien M; Hendriks, Marc Ph; Jansen, Jacobus Fa; Backes, Walter H; Hofman, Paul Am; Thoonen, Geert; Kessels, Roy Pc; Aldenkamp, Albert P

2013-06-04

Working memory is a temporary storage system under attentional control. It is believed to play a central role in online processing of complex cognitive information and may also play a role in social cognition and interpersonal interactions. Adolescents with a disorder on the autism spectrum display problems in precisely these domains. Social impairments, communication difficulties, and repetitive interests and activities are core domains of autism spectrum disorders (ASD), and executive function problems are often seen throughout the spectrum. As the main cognitive theories of ASD, including the theory of mind deficit hypotheses, weak central coherence account, and the executive dysfunction theory, still fail to explain the broad spectrum of symptoms, a new perspective on the etiology of ASD is needed. Deficits in working memory are central to many theories of psychopathology, and are generally linked to frontal-lobe dysfunction. This article will review neuropsychological and (functional) brain imaging studies on working memory in adolescents with ASD. Although still disputed, it is concluded that within the working memory system specific problems of spatial working memory are often seen in adolescents with ASD. These problems increase when information is more complex and greater demands on working memory are made. Neuroimaging studies indicate a more global working memory processing or connectivity deficiency, rather than a focused deficit in the prefrontal cortex. More research is needed to relate these working memory difficulties and neuroimaging results in ASD to the behavioral difficulties as seen in individuals with a disorder on the autism spectrum.

An impurity-induced gap system as a quantum data bus for quantum state transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Bing, E-mail: chenbingphys@gmail.com; Li, Yong; Song, Z.

2014-09-15

We introduce a tight-binding chain with a single impurity to act as a quantum data bus for perfect quantum state transfer. Our proposal is based on the weak coupling limit of the two outermost quantum dots to the data bus, which is a gapped system induced by the impurity. By connecting two quantum dots to two sites of the data bus, the system can accomplish a high-fidelity and long-distance quantum state transfer. Numerical simulations for finite system show that the numerical and analytical results of the effective coupling strength agree well with each other. Moreover, we study the robustness ofmore » this quantum communication protocol in the presence of disorder in the couplings between the nearest-neighbor quantum dots. We find that the gap of the system plays an important role in robust quantum state transfer.« less

Neurologic complications of electrolyte disturbances and acid-base balance.

PubMed

Espay, Alberto J

2014-01-01

Electrolyte and acid-base disturbances are common occurrences in daily clinical practice. Although these abnormalities can be readily ascertained from routine laboratory findings, only specific clinical correlates may attest as to their significance. Among a wide phenotypic spectrum, acute electrolyte and acid-base disturbances may affect the peripheral nervous system as arreflexic weakness (hypermagnesemia, hyperkalemia, and hypophosphatemia), the central nervous system as epileptic encephalopathies (hypomagnesemia, dysnatremias, and hypocalcemia), or both as a mixture of encephalopathy and weakness or paresthesias (hypocalcemia, alkalosis). Disabling complications may develop not only when these derangements are overlooked and left untreated (e.g., visual loss from intracranial hypertension in respiratory or metabolic acidosis; quadriplegia with respiratory insufficiency in hypermagnesemia) but also when they are inappropriately managed (e.g., central pontine myelinolisis when rapidly correcting hyponatremia; cardiac arrhythmias when aggressively correcting hypo- or hyperkalemia). Therefore prompt identification of the specific neurometabolic syndromes is critical to correct the causative electrolyte or acid-base disturbances and prevent permanent central or peripheral nervous system injury. This chapter reviews the pathophysiology, clinical investigations, clinical phenotypes, and current management strategies in disorders resulting from alterations in the plasma concentration of sodium, potassium, calcium, magnesium, and phosphorus as well as from acidemia and alkalemia. © 2014 Elsevier B.V. All rights reserved.

Distributional behavior of diffusion coefficients obtained by single trajectories in annealed transit time model

NASA Astrophysics Data System (ADS)

Akimoto, Takuma; Yamamoto, Eiji

2016-12-01

Local diffusion coefficients in disordered systems such as spin glass systems and living cells are highly heterogeneous and may change over time. Such a time-dependent and spatially heterogeneous environment results in irreproducibility of single-particle-tracking measurements. Irreproducibility of time-averaged observables has been theoretically studied in the context of weak ergodicity breaking in stochastic processes. Here, we provide rigorous descriptions of equilibrium and non-equilibrium diffusion processes for the annealed transit time model, which is a heterogeneous diffusion model in living cells. We give analytical solutions for the mean square displacement (MSD) and the relative standard deviation of the time-averaged MSD for equilibrium and non-equilibrium situations. We find that the time-averaged MSD grows linearly with time and that the time-averaged diffusion coefficients are intrinsically random (irreproducible) even in the long-time measurements in non-equilibrium situations. Furthermore, the distribution of the time-averaged diffusion coefficients converges to a universal distribution in the sense that it does not depend on initial conditions. Our findings pave the way for a theoretical understanding of distributional behavior of the time-averaged diffusion coefficients in disordered systems.

Protein disorder is positively correlated with gene expression in E. coli

PubMed Central

Paliy, Oleg; Gargac, Shawn M.; Cheng, Yugong; Uversky, Vladimir N.; Dunker, A. Keith

2009-01-01

We considered on a global scale the relationship between the predicted fraction of protein disorder and RNA and protein expression in E. coli. Fraction of protein disorder correlated positively with both measured RNA expression levels of E. coli genes in three different growth media and with predicted abundance levels of E. coli proteins. Though weak, the correlation was highly significant. Correlation of protein disorder with RNA expression did not depend on the growth rate of E. coli cultures and was not caused by a small subset of genes showing exceptionally high concordance in their disorder and expression levels. Global analysis was complemented by detailed consideration of several groups of proteins. PMID:18465893

(7-Chloro-2-oxo-2H-chromen-4-yl)methyl pyrrolidine-1-carbodi­thio­ate

PubMed Central

Kotresh, O.; Devarajegowda, H. C.; Shirahatti, Arunkumar; Kumar, K. Mahesh; Mahabhaleshwaraiah, N. M.

2013-01-01

In the title compound, C15H14ClNO2S2, the 2H-chromene ring system is essentially planar, with a maximum deviation of 0.0133 (10) Å. Three C atoms and their attached H atoms of the pyrrolidine ring are disordered [occupany ratio 0.874 (7):0.126 (7)] with both disorder components adopting a twisted conformation. The dihedral angle between the 2H-chromene ring system and the major occupancy component of the pyrrolidine ring is 89.45 (7)°. In the crystal, inversion dimers linked by pairs of C—H⋯S and C—H⋯O inter­actions generate R 2 2(24) and R 2 2(10) loops, respectively. Further C—H⋯O hydrogen bonds link the dimers into [100] chains. C—H⋯π inter­actions also occur and there is very weak π–π stacking [inter­planar spacing = 3.650 (5) Å; centroid–centroid distance = 4.095 (7) Å] between inversion-related chloro­benzene rings. PMID:24454115

Theory of Mind Deficit versus Faulty Procedural Memory in Autism Spectrum Disorders.

PubMed

Romero-Munguía, Miguel Ángel

2013-01-01

Individuals with autism spectrum disorders (ASD) have impairments in social interaction, communicative capacity, and behavioral flexibility (core triad). Three major cognitive theories (theory of mind deficit, weak central coherence, and executive dysfunction) seem to explain many of these impairments. Currently, however, the empathizing-systemizing (a newer version of the theory of mind deficit account) and mnesic imbalance theories are the only ones that attempt to explain all these core triadic symptoms of ASD On the other hand, theory of mind deficit in empathizing-systemizing theory is the most influential account for ASD, but its counterpart in the mnesic imbalance theory, faulty procedural memory, seems to occur earlier in development; consequently, this might be a better solution to the problem of the etiology of ASD, if it truly meets the precedence criterion. Hence, in the present paper I review the reasoning in favor of the theory of mind deficit but with a new interpretation based on the mnesic imbalance theory, which posits that faulty procedural memory causes deficits in several cognitive skills, resulting in poor performance in theory of mind tasks.

Theory of Mind Deficit versus Faulty Procedural Memory in Autism Spectrum Disorders

PubMed Central

Romero-Munguía, Miguel Ángel

2013-01-01

Individuals with autism spectrum disorders (ASD) have impairments in social interaction, communicative capacity, and behavioral flexibility (core triad). Three major cognitive theories (theory of mind deficit, weak central coherence, and executive dysfunction) seem to explain many of these impairments. Currently, however, the empathizing-systemizing (a newer version of the theory of mind deficit account) and mnesic imbalance theories are the only ones that attempt to explain all these core triadic symptoms of ASD On the other hand, theory of mind deficit in empathizing-systemizing theory is the most influential account for ASD, but its counterpart in the mnesic imbalance theory, faulty procedural memory, seems to occur earlier in development; consequently, this might be a better solution to the problem of the etiology of ASD, if it truly meets the precedence criterion. Hence, in the present paper I review the reasoning in favor of the theory of mind deficit but with a new interpretation based on the mnesic imbalance theory, which posits that faulty procedural memory causes deficits in several cognitive skills, resulting in poor performance in theory of mind tasks. PMID:23862063

2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion

NASA Astrophysics Data System (ADS)

Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning

2016-08-01

Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility.

"Hunting with a Knife and... Fork": Examining Central Coherence in Autism, Attention Deficit/Hyperactivity Disorder, and Typical Development with a Linguistic Task

ERIC Educational Resources Information Center

Booth, Rhonda; Happe, Francesca

2010-01-01

A local processing bias, referred to as "weak central coherence," has been postulated to underlie key aspects of autism spectrum disorder (ASD). Little research has examined whether individual differences in this cognitive style can be found in typical development, independent of intelligence, and how local processing relates to executive control.…

Idiopathic Inflammatory Myopathies

PubMed Central

Dimachkie, Mazen M.; Barohn, Richard J.

2012-01-01

The idiopathic inflammatory myopathies are a group of rare disorders including polymyositis (PM), dermatomyositis (DM), and autoimmune necrotizing myopathies (NMs). The idiopathic inflammatory myopathies share many similarities. They present acutely, subacutely, or chronically with marked proximal and symmetric muscle weakness, except for associated distal and asymmetric weakness in inclusion body myositis. The idiopathic inflammatory myopathies also share a variable degree of creatine kinase (CK) elevation and a nonspecifically abnormal electromyogram demonstrating an irritative myopathy. The muscle pathology demonstrates inflammatory exudates of variable distribution within the muscle fascicle. Despite these similarities, the idiopathic inflammatory myopathies are a heterogeneous group. The overlap syndrome (OS) refers to the association of PM, DM, or NM with connective tissue disease, such as scleroderma or systemic lupus erythematosus. In addition to elevated antinuclear antibodies (ANA), patients with OS may be weaker in the proximal arms than the legs mimicking the pattern seen in some muscular dystrophies. In this review, we focus on DM, PM, and NM and examine current and promising therapies. PMID:23117947

Generalized model of island biodiversity

NASA Astrophysics Data System (ADS)

Kessler, David A.; Shnerb, Nadav M.

2015-04-01

The dynamics of a local community of competing species with weak immigration from a static regional pool is studied. Implementing the generalized competitive Lotka-Volterra model with demographic noise, a rich dynamics with four qualitatively distinct phases is unfolded. When the overall interspecies competition is weak, the island species recapitulate the mainland species. For higher values of the competition parameter, the system still admits an equilibrium community, but now some of the mainland species are absent on the island. Further increase in competition leads to an intermittent "disordered" phase, where the dynamics is controlled by invadable combinations of species and the turnover rate is governed by the migration. Finally, the strong competition phase is glasslike, dominated by uninvadable states and noise-induced transitions. Our model contains, as a special case, the celebrated neutral island theories of Wilson-MacArthur and Hubbell. Moreover, we show that slight deviations from perfect neutrality may lead to each of the phases, as the Hubbell point appears to be quadracritical.

Generalized model of island biodiversity.

PubMed

Kessler, David A; Shnerb, Nadav M

2015-04-01

The dynamics of a local community of competing species with weak immigration from a static regional pool is studied. Implementing the generalized competitive Lotka-Volterra model with demographic noise, a rich dynamics with four qualitatively distinct phases is unfolded. When the overall interspecies competition is weak, the island species recapitulate the mainland species. For higher values of the competition parameter, the system still admits an equilibrium community, but now some of the mainland species are absent on the island. Further increase in competition leads to an intermittent "disordered" phase, where the dynamics is controlled by invadable combinations of species and the turnover rate is governed by the migration. Finally, the strong competition phase is glasslike, dominated by uninvadable states and noise-induced transitions. Our model contains, as a special case, the celebrated neutral island theories of Wilson-MacArthur and Hubbell. Moreover, we show that slight deviations from perfect neutrality may lead to each of the phases, as the Hubbell point appears to be quadracritical.

Genetics Home Reference: episodic ataxia

MedlinePlus

... vision, slurred speech, and ringing in the ears (tinnitus). Seizures, muscle weakness, and paralysis affecting one side ... autosomal dominant disorder with episodic ataxia, vertigo, and tinnitus. Neurology. 2001 Oct 23;57(8):1499-502. ...

Signature of phase singularities in diffusive regimes in disordered waveguide lattices: interplay and qualitative analysis

NASA Astrophysics Data System (ADS)

Ghosh, Somnath

2018-05-01

Co-existence and interplay between mesoscopic light dynamics with singular optics in spatially random but temporally coherent disordered waveguide lattices is reported. Two CW light beams of 1.55 micron operating wavelength are launched as inputs to 1D waveguide lattices with controllable weak disorder in refractive index profile. Direct observation of phase singularities in the speckle pattern along the length is numerically demonstrated. Quantitative analysis of onset of such singular behavior and diffusive wave propagation is analyzed for the first time.

Blonanserin Augmentation for Treatment-Resistant Somatic Symptom Disorder: A Case Series.

PubMed

Nagoshi, Yasuhide; Tominaga, Toshiyuki; Fukui, Kenji

2016-01-01

The augmentation of selective serotonin reuptake inhibitors with antipsychotics that have a high dopamine-receptor-D2 affinity may be effective in treatment-resistant obsessive-compulsive disorder and somatic symptom disorder, which is similar to illness anxiety disorder. Blonanserin, a novel antipsychotic developed in Japan, has a high affinity for the D2 receptor and weak or very little affinity for other receptors. This article presents two case studies that demonstrate the efficacy of blonanserin augmentation for treatment-resistant somatic symptom disorder. Two patients with treatment-resistant somatic symptom disorder were prescribed concomitant use of blonanserin. Augmentation with blonanserin resulted in the remarkable amelioration of all symptoms. Sedative adverse drug reactions produced by aripiprazole were improved after replacing it with blonanserin. Blonanserin is effective in treatment-resistant somatic symptom disorder. Furthermore, compared with aripiprazole, blonanserin is more likely to result in medication adherence in patients with somatic symptom disorder because it reduced adverse drug reactions.

The validity and clinical utility of purging disorder.

PubMed

Keel, Pamela K; Striegel-Moore, Ruth H

2009-12-01

To review evidence of the validity and clinical utility of Purging Disorder and examine options for the Diagnostic and Statistical Manual of Mental Disorders fifth edition (DSM-V). Articles were identified by computerized and manual searches and reviewed to address five questions about Purging Disorder: Is there "ample" literature? Is the syndrome clearly defined? Can it be measured and diagnosed reliably? Can it be differentiated from other eating disorders? Is there evidence of syndrome validity? Although empirical classification and concurrent validity studies provide emerging support for the distinctiveness of Purging Disorder, questions remain about definition, diagnostic reliability in clinical settings, and clinical utility (i.e., prognostic validity). We discuss strengths and weaknesses associated with various options for the status of Purging Disorder in the DSM-V ranging from making no changes from DSM-IV to designating Purging Disorder a diagnosis on equal footing with Anorexia Nervosa and Bulimia Nervosa.

Co-activation: its association with weakness and specific neurological pathology

PubMed Central

Busse, Monica E; Wiles, Charles M; van Deursen, Robert WM

2006-01-01

Background Net agonist muscle strength is in part determined by the degree of antagonist co-activation. The level of co-activation might vary in different neurological disorders causing weakness or might vary with agonist strength. Aim This study investigated whether antagonist co-activation changed a) with the degree of muscle weakness and b) with the nature of the neurological lesion causing weakness. Methods Measures of isometric quadriceps and hamstrings strength were obtained. Antagonist (hamstring) co-activation during knee extension was calculated as a ratio of hamstrings over quadriceps activity both during an isometric and during a functional sit to stand (STS) task (using kinematics) in groups of patients with extrapyramidal (n = 15), upper motor neuron (UMN) (n = 12), lower motor neuron (LMN) with (n = 18) or without (n = 12) sensory loss, primary muscle or neuromuscular junction disorder (n = 17) and in healthy matched controls (n = 32). Independent t-tests or Mann Witney U tests were used to compare between the groups. Correlations between variables were also investigated. Results In healthy subjects mean (SD) co-activation of hamstrings during isometric knee extension was 11.8 (6.2)% and during STS was 20.5 (12.9)%. In patients, co-activation ranged from 7 to 17% during isometric knee extension and 15 to 25% during STS. Only the extrapyramidal group had lower co-activation levels than healthy matched controls (p < 0.05). Agonist isometric muscle strength and co-activation correlated only in muscle disease (r = -0.6, p < 0.05) and during STS in UMN disorders (r = -0.7, p < 0.5). Conclusion It is concluded that antagonist co-activation does not systematically vary with the site of neurological pathology when compared to healthy matched controls or, in most patient groups, with strength. The lower co-activation levels found in the extrapyramidal group require confirmation and further investigation. Co-activation may be relevant to individuals with muscle weakness. Within patient serial studies in the presence of changing muscle strength may help to understand these relationships more clearly. PMID:17116259

Pediatric Myasthenia Gravis.

PubMed

Peragallo, Jason H

2017-05-01

Myasthenia gravis is a disorder of neuromuscular transmission that leads to fatigue of skeletal muscles and fluctuating weakness. Myasthenia that affects children can be classified into the following 3 forms: transient neonatal myasthenia, congenital myasthenic syndromes, and juvenile myasthenia gravis (JMG). JMG is an autoimmune disorder that has a tendency to affect the extraocular muscles, but can also affect all skeletal muscles leading to generalized weakness and fatigability. Respiratory muscles may be involved leading to respiratory failure requiring ventilator support. Diagnosis should be suspected clinically, and confirmatory diagnostic testing be performed, including serum acetylcholine receptor antibodies, repetitive nerve stimulation, and electromyography. Treatment for JMG includes acetylcholinesterase inhibitors, immunosuppressive medications, plasma exchange, intravenous immunoglobulins, and thymectomy. Children with myasthenia gravis require monitoring by a pediatric ophthalmologist for the development of amblyopia from ptosis or strabismus. Copyright © 2017 Elsevier Inc. All rights reserved.

Event schemas in autism spectrum disorders: the role of theory of mind and weak central coherence.

PubMed

Loth, Eva; Gómez, Juan Carlos; Happé, Francesca

2008-03-01

Event schemas (generalized knowledge of what happens at common real-life events, e.g., a birthday party) are an important cognitive tool for social understanding: They provide structure for social experiences while accounting for many variable aspects. Using an event narratives task, this study tested the hypotheses that theory of mind (ToM) deficits and weak central coherence (WCC, a local processing bias) undermine different aspects of event knowledge in people with autism spectrum disorder (ASD). Event narratives of ASD ToM-failers were overall significantly impaired. ASD ToM-passers showed more specific abnormalities relating to variable activities, and some of these were significantly associated to WCC. Abnormalities in event knowledge might help linking ASD-typical social deficits in real-life situations and the adherence to inflexible routines.

Prethermal time crystals in a one-dimensional periodically driven Floquet system

NASA Astrophysics Data System (ADS)

Zeng, Tian-Sheng; Sheng, D. N.

2017-09-01

Motivated by experimental observations of time-symmetry breaking behavior in a periodically driven (Floquet) system, we study a one-dimensional spin model to explore the stability of such Floquet discrete time crystals (DTCs) under the interplay between interaction and the microwave driving. For intermediate interactions and high drivings, from the time evolution of both stroboscopic spin polarization and mutual information between two ends, we show that Floquet DTCs can exist in a prethermal time regime without the tuning of strong disorder. For much weak interactions the system is a symmetry-unbroken phase, while for strong interactions it gives its way to a thermal phase. Through analyzing the entanglement dynamics, we show that large driving fields protect the prethermal DTCs from many-body localization and thermalization. Our results suggest that by increasing the spin interaction, one can drive the experimental system into optimal regime for observing a robust prethermal DTC phase.

[Gastroenterology in the G-DRG-System 2004].

PubMed

Bunzemeier, H; Frühmorgen, P; Caspary, W F; Roeder, N

2003-11-01

After a year of preliminary voluntarily introduction of casemix funding in hospitals in 2003 nearly every German hospital will be confronted with lump sump payments on the basis of the G-DRG system for their inpatient care starting from January 2004. To analyse weaknesses referring to gastroenterology services within the G-DRG version 1.0 the German Association for Disorders of the Digestive System and Metabolism (DGVS) and the DRG-Research-Group from the University of Muenster conducted a DRG evaluation project. In the analysis patient data from 16 hospitals were included. As a result of the project recommendations for G-DRG adjustments were generated. Those recommendations were implemented in the advancement to G-DRG version 2004. Also the International Classification of Diseases (ICD-10) was modified to ICD-10 German Modification. The classification of procedures OPS-301 was revised. The main adjustments to the G-DRG system and both classifications will be presented in this paper.

"Hunting with a knife and ... fork": examining central coherence in autism, attention deficit/hyperactivity disorder, and typical development with a linguistic task.

PubMed

Booth, Rhonda; Happé, Francesca

2010-12-01

A local processing bias, referred to as "weak central coherence," has been postulated to underlie key aspects of autism spectrum disorder (ASD). Little research has examined whether individual differences in this cognitive style can be found in typical development, independent of intelligence, and how local processing relates to executive control. We present a brief and easy-to-administer test of coherence requiring global sentence completions. We report results from three studies assessing (a) 176 typically developing (TD) 8- to 25-year-olds, (b) individuals with ASD and matched controls, and (c) matched groups with ASD or attention deficit/hyperactivity disorder (ADHD). The results suggest that the Sentence Completion Task can reveal individual differences in cognitive style unrelated to IQ in typical development, that most (but not all) people with ASD show weak coherence on this task, and that performance is not related to inhibitory control. The Sentence Completion Task was found to be a useful test instrument, capable of tapping local processing bias in a range of populations. (c) 2010 Elsevier Inc. All rights reserved.

Presynaptic Disorders: Lambert-Eaton Myasthenic Syndrome and Botulism.

PubMed

Gable, Karissa L; Massey, Janice M

2015-08-01

Lambert-Eaton myasthenic syndrome (LEMS) and botulism are acquired presynaptic nerve terminal disorders of the neuromuscular junction. Lambert-Eaton myasthenic syndrome is an idiopathic or paraneoplastic autoimmune syndrome in which autoantibodies of the P/Q-type voltage-gated calcium channel play a role in decreasing the release of acetylcholine, resulting in clinical symptoms of skeletal muscle weakness, diminished reflexes, and autonomic symptoms. Paraneoplastic LEMS is most often associated with small cell lung cancer. Diagnosis is confirmed by positive serologic testing and electrophysiological studies, which display characteristic features of low compound muscle action potentials, a decrement at 3Hz repetitive nerve stimulation, and facilitation with exercise or high-frequency repetitive stimulation. Treatment involves cancer monitoring and treatment, 3,4-diaminopyridine, immunosuppressive medications, and acetylcholinesterase inhibitors. Botulism is another presynaptic disorder of neuromuscular transmission. Clinical features classically involve cranial and bulbar palsies followed by descending weakness of the limbs, respiratory failure, and autonomic dysfunction. Electrodiagnostic testing is important in the evaluation and diagnosis. Treatment is supportive, and administration of antitoxin is beneficial in selected cases. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Metal-insulator transition in tin doped indium oxide (ITO) thin films: Quantum correction to the electrical conductivity

NASA Astrophysics Data System (ADS)

Kaushik, Deepak Kumar; Kumar, K. Uday; Subrahmanyam, A.

2017-01-01

Tin doped indium oxide (ITO) thin films are being used extensively as transparent conductors in several applications. In the present communication, we report the electrical transport in DC magnetron sputtered ITO thin films (prepared at 300 K and subsequently annealed at 673 K in vacuum for 60 minutes) in low temperatures (25-300 K). The low temperature Hall effect and resistivity measurements reveal that the ITO thin films are moderately dis-ordered (kFl˜1; kF is the Fermi wave vector and l is the electron mean free path) and degenerate semiconductors. The transport of charge carriers (electrons) in these disordered ITO thin films takes place via the de-localized states. The disorder effects lead to the well-known `metal-insulator transition' (MIT) which is observed at 110 K in these ITO thin films. The MIT in ITO thin films is explained by the quantum correction to the conductivity (QCC); this approach is based on the inclusion of quantum-mechanical interference effects in Boltzmann's expression of the conductivity of the disordered systems. The insulating behaviour observed in ITO thin films below the MIT temperature is attributed to the combined effect of the weak localization and the electron-electron interactions.

Neurofilaments Function as Shock Absorbers: Compression Response Arising from Disordered Proteins.

PubMed

Kornreich, Micha; Malka-Gibor, Eti; Zuker, Ben; Laser-Azogui, Adi; Beck, Roy

2016-09-30

What can cells gain by using disordered, rather than folded, proteins in the architecture of their skeleton? Disordered proteins take multiple coexisting conformations, and often contain segments which act as random-walk-shaped polymers. Using x-ray scattering we measure the compression response of disordered protein hydrogels, which are the main stress-responsive component of neuron cells. We find that at high compression their mechanics are dominated by gaslike steric and ionic repulsions. At low compression, specific attractive interactions dominate. This is demonstrated by the considerable hydrogel expansion induced by the truncation of critical short protein segments. Accordingly, the floppy disordered proteins form a weakly cross-bridged hydrogel, and act as shock absorbers that sustain large deformations without failure.

Neurofilaments Function as Shock Absorbers: Compression Response Arising from Disordered Proteins

NASA Astrophysics Data System (ADS)

Kornreich, Micha; Malka-Gibor, Eti; Zuker, Ben; Laser-Azogui, Adi; Beck, Roy

2016-09-01

What can cells gain by using disordered, rather than folded, proteins in the architecture of their skeleton? Disordered proteins take multiple coexisting conformations, and often contain segments which act as random-walk-shaped polymers. Using x-ray scattering we measure the compression response of disordered protein hydrogels, which are the main stress-responsive component of neuron cells. We find that at high compression their mechanics are dominated by gaslike steric and ionic repulsions. At low compression, specific attractive interactions dominate. This is demonstrated by the considerable hydrogel expansion induced by the truncation of critical short protein segments. Accordingly, the floppy disordered proteins form a weakly cross-bridged hydrogel, and act as shock absorbers that sustain large deformations without failure.

Symptoms of Internet Gaming Disorder in Youth: Predictors and Comorbidity.

PubMed

Wichstrøm, Lars; Stenseng, Frode; Belsky, Jay; von Soest, Tilmann; Hygen, Beate Wold

2018-04-05

Internet gaming disorder (IGD) was included in the Addendum to DSM-5 as a condition for further study. Studies of community samples using a diagnostic interview are lacking, and evaluations of the proposed symptoms, comorbidities, and predictors of IGD are scarce. To provide such information participants in a Norwegian prospective community study were assessed with a clinical interview at age 10 years. Symptoms of other psychiatric disorders were measured with the Child and Adolescent Psychiatric Assessment at ages 8 and 10 (n = 740). Children, parents, and teachers provided information on demographics, temperament, intelligence, executive functions, self-concept, social skills, victimization, emotion regulation, family climate, and parenting. Results indicated that IGD was present in 1.7% (95% confidence interval, 0.7-2.7) of the participants (3.0% boys and 0.5% girls). Factor analysis revealed two factors: heavy involvement and negative consequences. The positive predictive value of withdrawal, tolerance, and unsuccessful attempts to control gaming symptoms to the disorder was low. Symptoms of other common disorders correlated weakly with IGD-symptoms (i.e., from r = 0.07 to r = 0.15). Upon adjusting for gender and gaming at age 8, only limited social and emotion regulation skills at age 8 predicted more age-10 IGD symptoms. In conclusion, IGD is already present in a small percentage of Norwegian 10-year olds. At least three of the proposed symptoms -- withdrawal, tolerance and unsuccessful attempts to control gaming -- merit further study given their weak associations with the disorder. Symptoms of IGD are only marginally associated with symptoms of other psychiatric disorders and only predicted by social skills and emotion regulation deficits.

The association of posttraumatic stress disorder, complex posttraumatic stress disorder, and borderline personality disorder from a network analytical perspective.

PubMed

Knefel, Matthias; Tran, Ulrich S; Lueger-Schuster, Brigitte

2016-10-01

Posttraumatic Stress Disorder (PTSD), Complex PTSD, and Borderline Personality Disorder (BPD) share etiological risk factors and an overlapping set of associated symptoms. Since the ICD-11 proposal for trauma-related disorders, the relationship of these disorders has to be clarified. A novel approach to psychopathology, network analysis, allows for a detailed analysis of comorbidity on symptom level. Symptoms were assessed in adult survivors of childhood abuse (N=219) using the newly developed ICD-11 Trauma-Questionnaire and the SCID-II. The psychopathological network was analyzed using the network approach. PTSD and Complex PTSD symptoms were strongly connected within disorders and to a lesser degree between disorders. Symptoms of BPD were weakly connected to others. Re-experiencing and dissociation were the most central symptoms. Mental disorders are no discrete entities, clear boundaries are unlikely to be found. The psychopathological network revealed central symptoms that might be important targets for specific first interventions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multiple endocrine neoplasia (MEN) I

MedlinePlus

... at any age, and it affects men and women equally. A family history of this disorder raises your risk. ... interest Fatigue Headache Lack of menstrual periods (in women) Loss ... to the cold Unintentional weight loss Vision problems Weakness

Finger extension weakness and downbeat nystagmus motor neuron disease syndrome: A novel motor neuron disorder?

PubMed

Delva, Aline; Thakore, Nimish; Pioro, Erik P; Poesen, Koen; Saunders-Pullman, Rachel; Meijer, Inge A; Rucker, Janet C; Kissel, John T; Van Damme, Philip

2017-12-01

Disturbances of eye movements are infrequently encountered in motor neuron diseases (MNDs) or motor neuropathies, and there is no known syndrome that combines progressive muscle weakness with downbeat nystagmus. To describe the core clinical features of a syndrome of MND associated with downbeat nystagmus, clinical features were collected from 6 patients. All patients had slowly progressive muscle weakness and wasting in combination with downbeat nystagmus, which was clinically most obvious in downward and lateral gaze. Onset was in the second to fourth decade with finger extension weakness, progressing to other distal and sometimes more proximal muscles. Visual complaints were not always present. Electrodiagnostic testing showed signs of regional motor axonal loss in all patients. The etiology of this syndrome remains elusive. Because finger extension weakness and downbeat nystagmus are the discriminating clinical features of this MND, we propose the name FEWDON-MND syndrome. Muscle Nerve 56: 1164-1168, 2017. © 2017 The Authors Muscle & Nerve Published by Wiley Periodicals, Inc.

Finger extension weakness and downbeat nystagmus motor neuron disease syndrome: A novel motor neuron disorder?

PubMed Central

Delva, Aline; Thakore, Nimish; Pioro, Erik P.; Poesen, Koen; Saunders‐Pullman, Rachel; Meijer, Inge A.; Rucker, Janet C.; Kissel, John T.

2017-01-01

ABSTACT Introduction: Disturbances of eye movements are infrequently encountered in motor neuron diseases (MNDs) or motor neuropathies, and there is no known syndrome that combines progressive muscle weakness with downbeat nystagmus. Methods: To describe the core clinical features of a syndrome of MND associated with downbeat nystagmus, clinical features were collected from 6 patients. Results: All patients had slowly progressive muscle weakness and wasting in combination with downbeat nystagmus, which was clinically most obvious in downward and lateral gaze. Onset was in the second to fourth decade with finger extension weakness, progressing to other distal and sometimes more proximal muscles. Visual complaints were not always present. Electrodiagnostic testing showed signs of regional motor axonal loss in all patients. Discussion: The etiology of this syndrome remains elusive. Because finger extension weakness and downbeat nystagmus are the discriminating clinical features of this MND, we propose the name FEWDON‐MND syndrome. Muscle Nerve 56: 1164–1168, 2017 PMID:28440863

Trapping proton transfer intermediates in the disordered hydrogen-bonded network of cryogenic hydrofluoric acid solutions.

PubMed

Ayotte, Patrick; Plessis, Sylvain; Marchand, Patrick

2008-08-28

A molecular-level description of the structural and dynamical aspects that are responsible for the weak acid behaviour of dilute hydrofluoric acid solutions and their unusual increased acidity at near equimolar concentrations continues to elude us. We address this problem by reporting reflection-absorption infrared spectra (RAIRS) of cryogenic HF-H(2)O binary mixtures at various compositions prepared as nanoscopic films using molecular beam techniques. Optical constants for these cryogenic solutions [n(omega) and k(omega)] are obtained by iteratively solving Fresnel equations for stratified media. Modeling of the experimental RAIRS spectra allow for a quantitative interpretation of the complex interplay between multiple reflections, optical interference and absorption effects. The evolution of the strong absorption features in the intermediate 1000-3000 cm(-1) range with increasing HF concentration reveals the presence of various ionic dissociation intermediates that are trapped in the disordered H-bonded network of cryogenic hydrofluoric acid solutions. Our findings are discussed in light of the conventional interpretation of why hydrofluoric acid is a weak acid revealing molecular-level details of the mechanism for HF ionization that may be relevant to analogous elementary processes involved in the ionization of weak acids in aqueous solutions.

Linguistic profile of individuals with Down syndrome: comparing the linguistic performance of three developmental disorders.

PubMed

Ypsilanti, A; Grouios, G

2008-03-01

An increasing number of studies, addressing the linguistic abilities of individuals with Down syndrome (DS) suggest that they exhibit strengths and weaknesses within the linguistic domain. This article critically reviews the literature on the linguistic profile of individuals with DS, with particular emphasis on the expression and reception of vocabulary and grammar, including nonverbal linguistic expression during infant development. In doing so, attention is given to recent comparative studies of the linguistic abilities of individuals with DS, Specific Language Impairment (SLI), and Williams syndrome (WS). The possibility that deficits in one cognitive system may have consequences in another cognitive system, and that these consequences may define the nature of the impairment in each clinical syndrome is further discussed with suggestions for future research.

Neurocognitive, mental health, and glucose disorders in farmers exposed to organophosphorus pesticides.

PubMed

Malekirad, Ali Akbar; Faghih, Mahya; Mirabdollahi, Mansuoreh; Kiani, Mahdi; Fathi, Arezoo; Abdollahi, Mohammad

2013-01-01

About 25 million agricultural workers in the developing world suffer from at least one episode of poisoning each year, mainly by anticholinesterase-like organophosphates (OPs). The objective of this cross-sectional study was to establish the OP toxicity in 187 occupationally exposed farmers in terms of neurocognitive impairment, mental health status, clinical symptoms, diabetes, and haematological factors. The exposed group was compared to 187 healthy age-, sex-, and education-matching controls. Neurocognitive impairment was measured using the Subjective Neurocognition Inventory (SNI) and mental health status using the General Health Questionnaire-28 (GHQ-28). The subjects were also tested for fasting blood glucose (FBG), blood urea nitrogen (BUN), cholesterol (CL), triglycerides (TG), creatinine, oral glucose tolerance test (GTT), high-density lipoprotein (HDL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). The exposed farmers showed higher FBG (p<0.001), BUN (p=0.007), CL (p<0.001), oral GTT (p<0.001), and lower AST (p<0.001), ALP (p<0.001), and creatinine (p=0.004) than controls. The rates of anxiety/ insomnia and severe depression were also significantly higher in the farmers than in controls (p=0.015 and p<0.001, respectively). Meanwhile, the rate of social dysfunction was significantly lower than in controls (p<0.001). Disorders affecting psychomotor speed, selective attention, divided attention, verbal memory, nonverbal memory, prospective memory, spatial functioning, and initiative/energy were all lower in the farmers (p<0.001). Farmers showed clinical symptoms eczema, saliva secretion, fatigue, headache, sweating, abdominal pain, nausea, superior distal muscle weakness, inferior distal muscle weakness, inferior proximal muscle weakness, breath muscle weakness, hand tingling, foot tingling, epiphoria, polyuria, miosis, dyspnoea, bradycardia, and rhinorrhoea, which all significantly correlated with the number of working years. These findings indicate that farmers who work with OPs are prone to neuropsychological disorders and diabetes.

[Correlation factors of 127 times pre-crisis state in patients with myasthenia gravis].

PubMed

Ou, C Y; Ran, H; Qiu, L; Huang, Z D; Lin, Z Z; Deng, J; Liu, W B

2017-10-10

Objective: To investigate the clinical features of the Pre-Crisis State and analyze the correlated risk factors of Pre-Crisis State of myasthenia crisis. Methods: We included 93 patients with myasthenia gravis (MG) who experienced 127 times Pre-Crisis State between October 2007 and July 2016. Those patients were hospitalized in the MG specialize center, Department of Neurological Science, first Affiliated Hospital of Sun Yat-sen University. The information of the general situation, the clinical manifestations and the blood gas analysis in those patients were collected using our innovated clinical research form. Statistic methods were applied including descriptive analysis, univariate logistic analysis, multivariate correlation logistic analysis, etc. Results: (1)The typical features of MG Pre-Crisis State included: dyspnea (127 times, 100% not requiring intubation or non-invasive ventilation), bulbar-muscle weakness (121 times, 95.28%), the increased blood partial pressure of carbon dioxide (PCO(2)) (94 times, 85.45%), expectoration weakness (99 times, 77.95%), sleep disorders (107 times, 84.25%) and the infection (99 times, 77.95%). The occurrence of dyspnea in combination with bulbar-muscle weakness ( P =0.002) or the increased blood PCO(2) ( P =0.042) often indicated the tendency of crisis. (2) The MG symptoms which were proportion to the occurrence of crisis includes: bulbar-muscle weakness ( P =0.028), fever ( P =0.028), malnutrition ( P =0.066), complications ( P =0.071), excess oropharyngeal secretions ( P =0.005) and the increased blood PCO(2) ( P =0.007). The perioperative period of thymectomy would not increase the risk of crisis. Conclusions: Dyspnea indicates the occurrence of the Pre-Crisis State of MG. In order to significantly reduce the morbidity of myasthenia crisis, the bulbar-muscle weakness, the increased blood PCO(2), expectoration weakness, sleep disorders, infection & fever and excess oropharyngeal secretions should be treated timely.

Signature of phase singularities in diffusive regimes in disordered waveguide lattices: interplay and qualitative analysis.

PubMed

Ghosh, Somnath

2018-05-10

Coexistence and interplay between mesoscopic light dynamics with singular optics in spatially disordered waveguide lattices are reported. Two CW light beams of a 1.55 μm operating wavelength are launched as inputs to 1D waveguide lattices with controllable weak disorder in a complex refractive index profile. Direct observation of phase singularities in the speckle pattern along the length is numerically demonstrated. Quantitative analysis of the onset of such singular behavior and diffusive wave propagation is analyzed for the first time, to the best of our knowledge.

Transport of a Bose gas in 1D disordered lattices at the fluid-insulator transition.

PubMed

Tanzi, Luca; Lucioni, Eleonora; Chaudhuri, Saptarishi; Gori, Lorenzo; Kumar, Avinash; D'Errico, Chiara; Inguscio, Massimo; Modugno, Giovanni

2013-09-13

We investigate the momentum-dependent transport of 1D quasicondensates in quasiperiodic optical lattices. We observe a sharp crossover from a weakly dissipative regime to a strongly unstable one at a disorder-dependent critical momentum. In the limit of nondisordered lattices the observations suggest a contribution of quantum phase slips to the dissipation. We identify a set of critical disorder and interaction strengths for which such critical momentum vanishes, separating a fluid regime from an insulating one. We relate our observation to the predicted zero-temperature superfluid-Bose glass transition.

Levitation of current carrying states in the lattice model for the integer quantum Hall effect.

PubMed

Koschny, T; Potempa, H; Schweitzer, L

2001-04-23

The disorder driven quantum Hall to insulator transition is investigated for a two-dimensional lattice model. The Hall conductivity and the localization length are calculated numerically near the transition. For uncorrelated and weakly correlated disorder potentials the current carrying states are annihilated by the negative Chern states originating from the band center. In the presence of correlated disorder potentials with correlation length larger than approximately half the lattice constant the floating up of the critical states in energy without merging is observed. This behavior is similar to the levitation scenario proposed for the continuum model.

Local visual perception bias in children with high-functioning autism spectrum disorders; do we have the whole picture?

PubMed

Falkmer, Marita; Black, Melissa; Tang, Julia; Fitzgerald, Patrick; Girdler, Sonya; Leung, Denise; Ordqvist, Anna; Tan, Tele; Jahan, Ishrat; Falkmer, Torbjorn

2016-01-01

While local bias in visual processing in children with autism spectrum disorders (ASD) has been reported to result in difficulties in recognizing faces and facially expressed emotions, but superior ability in disembedding figures, associations between these abilities within a group of children with and without ASD have not been explored. Possible associations in performance on the Visual Perception Skills Figure-Ground test, a face recognition test and an emotion recognition test were investigated within 25 8-12-years-old children with high-functioning autism/Asperger syndrome, and in comparison to 33 typically developing children. Analyses indicated a weak positive correlation between accuracy in Figure-Ground recognition and emotion recognition. No other correlation estimates were significant. These findings challenge both the enhanced perceptual function hypothesis and the weak central coherence hypothesis, and accentuate the importance of further scrutinizing the existance and nature of local visual bias in ASD.

Osteogenesis Imperfecta: Muscle-Bone Interactions when Bi-directionally Compromised.

PubMed

Phillips, Charlotte L; Jeong, Youngjae

2018-06-16

Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder of skeletal fragility and more recently muscle weakness. This review highlights our current knowledge of the impact of compromised OI muscle function on muscle-bone interactions and skeletal strength in OI. The ramifications of inherent muscle weakness in OI muscle-bone interactions are just beginning to be elucidated. Studies in patients and in OI mouse models implicate altered mechanosensing, energy metabolism, mitochondrial dysfunction, and paracrine/endocrine crosstalk in the pathogenesis of OI. Compromised muscle-bone unit impacts mechanosensing and the ability of OI muscle and bone to respond to physiotherapeutic and pharmacologic treatment strategies. Muscle and bone are both compromised in OI, making it essential to understand the mechanisms responsible for both impaired muscle and bone functions and their interdependence, as this will expand and drive new physiotherapeutic and pharmacological approaches to treat OI and other musculoskeletal disorders.

Interacting damage models mapped onto ising and percolation models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toussaint, Renaud; Pride, Steven R.

The authors introduce a class of damage models on regular lattices with isotropic interactions between the broken cells of the lattice. Quasistatic fiber bundles are an example. The interactions are assumed to be weak, in the sense that the stress perturbation from a broken cell is much smaller than the mean stress in the system. The system starts intact with a surface-energy threshold required to break any cell sampled from an uncorrelated quenched-disorder distribution. The evolution of this heterogeneous system is ruled by Griffith's principle which states that a cell breaks when the release in potential (elastic) energy in themore » system exceeds the surface-energy barrier necessary to break the cell. By direct integration over all possible realizations of the quenched disorder, they obtain the probability distribution of each damage configuration at any level of the imposed external deformation. They demonstrate an isomorphism between the distributions so obtained and standard generalized Ising models, in which the coupling constants and effective temperature in the Ising model are functions of the nature of the quenched-disorder distribution and the extent of accumulated damage. In particular, they show that damage models with global load sharing are isomorphic to standard percolation theory, that damage models with local load sharing rule are isomorphic to the standard ising model, and draw consequences thereof for the universality class and behavior of the autocorrelation length of the breakdown transitions corresponding to these models. they also treat damage models having more general power-law interactions, and classify the breakdown process as a function of the power-law interaction exponent. Last, they also show that the probability distribution over configurations is a maximum of Shannon's entropy under some specific constraints related to the energetic balance of the fracture process, which firmly relates this type of quenched-disorder based damage model to standard statistical mechanics.« less

Rapid Linguistic Ambiguity Resolution in Young Children with Autism Spectrum Disorder: Eye Tracking Evidence for the Limits of Weak Central Coherence.

PubMed

Hahn, Noemi; Snedeker, Jesse; Rabagliati, Hugh

2015-12-01

Individuals with autism spectrum disorders (ASD) have often been reported to have difficulty integrating information into its broader context, which has motivated the Weak Central Coherence theory of ASD. In the linguistic domain, evidence for this difficulty comes from reports of impaired use of linguistic context to resolve ambiguous words. However, recent work has suggested that impaired use of linguistic context may not be characteristic of ASD, and is instead better explained by co-occurring language impairments. Here, we provide a strong test of these claims, using the visual world eye tracking paradigm to examine the online mechanisms by which children with autism resolve linguistic ambiguity. To address concerns about both language impairments and compensatory strategies, we used a sample whose verbal skills were strong and whose average age (7; 6) was lower than previous work on lexical ambiguity resolution in ASD. Participants (40 with autism and 40 controls) heard sentences with ambiguous words in contexts that either strongly supported one reading or were consistent with both (John fed/saw the bat). We measured activation of the unintended meaning through implicit semantic priming of an associate (looks to a depicted baseball glove). Contrary to the predictions of weak central coherence, children with ASD, like controls, quickly used context to resolve ambiguity, selecting appropriate meanings within a second. We discuss how these results constrain the generality of weak central coherence. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.

Factors for drop-out psychiatric treatment in patients with substance-related disorders.

PubMed

Masaki, Naoko; Toyomasu, Koji

2010-01-01

We studied 199 inpatients and outpatients at a public psychiatric hospital to clarify the factors related to outcome following psychiatric care for substance-related disorder (SRD), and we discuss approaches for more effective community care in the future. The percentage of patients who discontinued treatment was 33.7%, suggesting that creation of a follow-up system for continuing outpatient care is an urgent task. Women were 35% more likely higher to discontinue treatment than men. Those with solvent dependence were 12% and 7.32 times more likely, respectively, to discontinue treatment than those with alcohol dependence. Those without complications were 2.24 times more likely than those with complications to discontinue treatment. Divorced patients were 18% and 6.35 times more likely, respectively, to discontinue treatment than married patients. There is insufficient support for patients with solvent dependence, and we observed that patients tended to have little motivation to stop using drugs or alcohol until physical complications occurred. Among the many divorced patients, desire for treatment was weak following breakdown of the family. The present findings suggest the importance of comprehensive efforts to treat substance use disorder at specialist medical institutions.

Correlation of the Rock Mass Rating (RMR) System with the Unified Soil Classification System (USCS): Introduction of the Weak Rock Mass Rating System (W-RMR)

NASA Astrophysics Data System (ADS)

Warren, Sean N.; Kallu, Raj R.; Barnard, Chase K.

2016-11-01

Underground gold mines in Nevada are exploiting increasingly deeper ore bodies comprised of weak to very weak rock masses. The Rock Mass Rating (RMR) classification system is widely used at underground gold mines in Nevada and is applicable in fair to good-quality rock masses, but is difficult to apply and loses reliability in very weak rock mass to soil-like material. Because very weak rock masses are transition materials that border engineering rock mass and soil classification systems, soil classification may sometimes be easier and more appropriate to provide insight into material behavior and properties. The Unified Soil Classification System (USCS) is the most likely choice for the classification of very weak rock mass to soil-like material because of its accepted use in tunnel engineering projects and its ability to predict soil-like material behavior underground. A correlation between the RMR and USCS systems was developed by comparing underground geotechnical RMR mapping to laboratory testing of bulk samples from the same locations, thereby assigning a numeric RMR value to the USCS classification that can be used in spreadsheet calculations and geostatistical analyses. The geotechnical classification system presented in this paper including a USCS-RMR correlation, RMR rating equations, and the Geo-Pick Strike Index is collectively introduced as the Weak Rock Mass Rating System (W-RMR). It is the authors' hope that this system will aid in the classification of weak rock masses and more usable design tools based on the RMR system. More broadly, the RMR-USCS correlation and the W-RMR system help define the transition between engineering soil and rock mass classification systems and may provide insight for geotechnical design in very weak rock masses.

Congenital myasthenic syndrome with tubular aggregates caused by GFPT1 mutations.

PubMed

Guergueltcheva, Velina; Müller, Juliane S; Dusl, Marina; Senderek, Jan; Oldfors, Anders; Lindbergh, Christopher; Maxwell, Susan; Colomer, Jaume; Mallebrera, Cecilia Jimenez; Nascimento, Andres; Vilchez, Juan J; Muelas, Nuria; Kirschner, Janbernd; Nafissi, Shahriar; Kariminejad, Ariana; Nilipour, Yalda; Bozorgmehr, Bita; Najmabadi, Hossein; Rodolico, Carmelo; Sieb, Jörn P; Schlotter, Beate; Schoser, Benedikt; Herrmann, Ralf; Voit, Thomas; Steinlein, Ortrud K; Najafi, Abdolhamid; Urtizberea, Andoni; Soler, Doriette M; Muntoni, Francesco; Hanna, Michael G; Chaouch, Amina; Straub, Volker; Bushby, Kate; Palace, Jacqueline; Beeson, David; Abicht, Angela; Lochmüller, Hanns

2012-05-01

Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous group of inherited disorders of the neuromuscular junction. A difficult to diagnose subgroup of CMS is characterised by proximal muscle weakness and fatigue while ocular and facial involvement is only minimal. DOK7 mutations have been identified as causing the disorder in about half of the cases. More recently, using classical positional cloning, we have identified mutations in a previously unrecognised CMS gene, GFPT1, in a series of DOK7-negative cases. However, detailed description of clinical features of GFPT1 patients has not been reported yet. Here we describe the clinical picture of 24 limb-girdle CMS (LG-CMS) patients and pathological findings of 18 of them, all carrying GFPT1 mutations. Additional patients with CMS, but without tubular aggregates, and patients with non-fatigable weakness with tubular aggregates were also screened. In most patients with GFPT1 mutations, onset of the disease occurs in the first decade of life with characteristic limb-girdle weakness and fatigue. A common feature was beneficial and sustained response to acetylcholinesterase inhibitor treatment. Most of the patients who had a muscle biopsy showed tubular aggregates in myofibers. Analysis of endplate morphology in one of the patients revealed unspecific abnormalities. Our study delineates the phenotype of CMS associated with GFPT1 mutations and expands the understanding of neuromuscular junction disorders. As tubular aggregates in context of a neuromuscular transmission defect appear to be highly indicative, we suggest calling this condition congenital myasthenic syndrome with tubular aggregates (CMS-TA).

Meta-analysis of the association between suicidal ideation and later suicide among patients with either a schizophrenia spectrum psychosis or a mood disorder.

PubMed

Chapman, C L; Mullin, K; Ryan, C J; Kuffel, A; Nielssen, O; Large, M M

2015-03-01

Recent studies of patients with a mix of psychiatric diagnoses have suggested a modest or weak association between suicidal ideation and later suicide. The aim of this study was to examine the extent to which the association between expressed suicidal ideation and later suicide varies according to psychiatric diagnosis. A systematic meta-analysis of studies that report the association between suicidal ideation and later suicide in patients with 'mood disorders', defined to include major depression, dysthymia and bipolar disorder, or 'schizophrenia spectrum psychosis', defined to include schizophrenia, schizophreniform disorder and delusional disorder. Suicidal ideation was strongly associated with suicide among patients with schizophrenia spectrum psychosis [14 studies reporting on 567 suicides, OR = 6.49, 95% confidence interval (CI) 3.82-11.02]. The association between suicidal ideation and suicide among patients with mood disorders (11 studies reporting on 860 suicides, OR = 1.49, 95% CI 0.92-2.42) was not significant. Diagnostic group made a significant contribution to between-study heterogeneity (Q-value = 16.2, df = 1, P < 0.001) indicating a significant difference in the strength of the associations between suicidal ideation and suicide between the two diagnostic groups. Meta-regression and multiple meta-regression suggested that methodological issues in the primary research did not explain the findings. Suicidal ideation was weakly but significantly associated with suicide among studies of patients with mood disorders over periods of follow-up of <10 years. Although our findings suggest that the association between suicidal ideation and later suicide is stronger in schizophrenia spectrum psychosis than in mood disorders this result should be interpreted cautiously due to the high degree of between-study heterogeneity and because studies that used stronger methods of reporting had a weaker association between suicidal ideation and suicide. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Anti-nuclear autoantibodies in the general German population: prevalence and lack of association with selected cardiovascular and metabolic disorders-findings of a multicenter population-based study.

PubMed

Akmatov, Manas K; Röber, Nadja; Ahrens, Wolfgang; Flesch-Janys, Dieter; Fricke, Julia; Greiser, Halina; Günther, Kathrin; Kaaks, Rudolf; Kemmling, Yvonne; Krone, Bastian; Linseisen, Jakob; Meisinger, Christa; Moebus, Susanne; Obi, Nadia; Guzman, Carlos A; Conrad, Karsten; Pessler, Frank

2017-06-06

We determined the prevalence of anti-nuclear autoantibodies (ANAs) in the German adult population and examined the association between ANAs and cardiovascular and metabolic disorders. We used data and blood samples from the pretest phases of the German National Cohort, obtained from six of the 18 study centers (n = 1199). All centers applied standardized instruments including face-to-face interviews, anthropometric measurements and collection of blood samples. Self-reported histories of diabetes mellitus, heart attack and elevated blood cholesterol and/or lipids were recorded. Height, weight and blood pressure were measured. ANAs were detected using a semi-automated system (AKLIDES®; Medipan GmbH, Dahlewitz, Germany). A positive ANA was defined as a titer ≥ 1:80. ANA were classified as weakly (1:80 or 1:160), moderately (1:320 or 1:640) or strongly (≥1:1280) positive. Specific autoantibodies against nuclear antigens were detected with second-step assays according to the ANA staining pattern. Associations between the assessed disorders and ANA positivity and pattern were examined using sex and age-adjusted mixed-effects logistic regression models. Thirty-three percent (95% confidence interval; 31-36%) of the 1196 participants (measurements could not be obtained from three samples) were ANA positive (titer ≥ 1:80). The proportions of weakly, moderately and strongly positive ANA were 29%, 3.3% and 1.3%, respectively. ANA positivity was more common among women than men across all titers (χ 2 , p = 0.03). ANA positivity, even when stratified according to height of titer or immunofluorescent pattern, was not associated with diabetes, elevated blood cholesterol and/or lipids, obesity or hypertension. Second-step autoantibody assays were positive in 41 of the 83 samples (49%) tested, with anti-DFS70 (n = 13) and anti-dsDNA (n = 7) being most frequent. These subgroups were too small to test for associations with the disorders assessed. The prevalence of ANA positivity in the German general population was similar to values reported from other countries. Contrary to other studies, there was no association with selected self-reported and objectively measured cardiovascular and metabolic variables.

Lives in isolation: stories and struggles of low-income African American women with panic disorder.

PubMed

Johnson, Michael; Mills, Terry L; Deleon, Jessica M; Hartzema, Abraham G; Haddad, Judella

2009-01-01

Research evidence points to the existence of racial-ethnic disparities in both access to and quality of mental health services for African Americans with panic disorder. Current panic disorder evaluation and treatment paradigms are not responsive to the needs of many African Americans. The primary individual, social, and health-care system factors that limit African Americans' access to care and response to treatment are not well understood. Low-income African American women with panic disorder participated in a series of focus-group sessions designed to elicit (1) their perspectives regarding access and treatment barriers and (2) their recommendations for designing a culturally consistent panic treatment program. Fear of confiding to others about panic symptoms, fear of social stigma, and lack of information about panic disorder were major individual barriers. Within their social networks, stigmatizing attitudes toward mental illness and the mentally ill, discouragement about the use of psychiatric medication, and perceptions that symptoms were the result of personal or spiritual weakness had all interfered with the participants' treatment seeking efforts and contributed to a common experience of severe social isolation. None of the focus-group members had developed fully effective therapeutic relationships with either medical or mental health providers. They described an unmet need for more interactive and culturally authentic relationships with treatment providers. Although the focus-group sessions were not intended to be therapeutic, the women reported that participation in the meetings had been an emotionally powerful and beneficial experience. They expressed a strong preference for the utilization of female-only, panic disorder peer-support groups as an initial step in the treatment/recovery process. Peer-support groups for low-income African American women with panic disorder could address many of the identified access and treatment barriers.

Myotonic Dystrophy Type 1 Management and Therapeutics.

PubMed

Smith, Cheryl A; Gutmann, Laurie

2016-12-01

Myotonic dystrophy (DM1) is the most common form of adult muscular dystrophy. It is a multisystem disorder with a complex pathophysiology. Although inheritance is autosomal dominant, disease variability is attributed to anticipation, a maternal expansion bias, variable penetrance, somatic mosaicism, and a multitude of aberrant pre-mRNA splicing events. Patient presentations range from asymptomatic or mild late onset adult to severe congenital forms. Multiple organ systems may be affected. Patients may experience early cataracts, myotonia, muscle weakness/atrophy, fatigue, excessive daytime sleepiness, central/obstructive apnea, respiratory failure, cardiac arrhythmia, insulin resistance, dysphagia, GI dysmotility, cognitive impairment, Cluster C personality traits, and/or mood disorders. At present, there is no curative or disease-modifying treatment, although clinical treatment trials have become more promising. Management focuses on genetic counseling, preserving function and independence, preventing cardiopulmonary complications, and symptomatic treatment (e.g., pain, myotonia, hypersomnolence, etc.). Currently, there is an increasing international consensus on monitoring and treatment options for these patients which necessitates a multidisciplinary team to provide comprehensive, coordinated clinical care.

Are There Disorders or Conditions Associated with Primary Ovarian Insufficiency (POI)?

MedlinePlus

... osteoporosis. Osteoporosis is a bone disease that causes weak, brittle bones that are more likely to break ... and Gynecologists. (2009). Premature ovarian failure. ACOG medical student teaching module [PowerPoint slides] . Retrieved January 3, 2012, ...

Exploratory Research on Latent Esophageal Motility Disorders in Dysphagia Patients.

PubMed

Kawaguchi, Shinpei; Takeuchi, Toshihisa; Inoue, Yousuke; Takahashi, Yoshiaki; Ozaki, Haruhiko; Ota, Kazuhiro; Harada, Satoshi; Edogawa, Shoko; Kojima, Yuichi; Yamashita, Hiroshi; Fukuchi, Takumi; Ashida, Kiyoshi; Higuchi, Kazuhide

2017-01-01

High-resolution manometry (HRM) has been applied to assess esophageal motility disorders. However, the frequency and types of motility disorders in patients with dysphagia, which are frequently seen in clinical practice, are not clear. We evaluated latent esophageal motility disorders associated with dysphagia. The study included patients without erosive esophageal mucosal damage and with dysphagia symptoms refractory to at least 8 weeks of standard-dose proton pump inhibitors. After enrolment, HRM was used to evaluate for esophageal motility disorder based on the Chicago classification. Esophageal motility disorder was found in 58 of 100 patients and was classified based on the causes: achalasia (13%), esophagogastric junction outflow obstruction (16%), distal esophageal spasms (3%), weak peristalsis (14%), frequently failed peristalsis (5%), and hypertensive peristalsis (7%). Primary esophageal motility disorder was found in approximately 50% of cases in dysphagia patients. Therefore, esophageal motility disorder is not an uncommon condition and should be sought for in order to elucidate precisely the cause of dysphagia. © 2017 S. Karger AG, Basel.

People With Cerebral Palsy: Effects of and Perspectives for Therapy

PubMed Central

Mayston, Margaret J.

2001-01-01

The movement disorder of cerebral palsy (CP) is expressed in a variety of ways and to varying degrees in each individual. The condition has become more complex over the last 20 years with the increasing survival of children born at less than 28 to 30 weeks gestationai age. Impairments present in children with CP as a direct result of the brain injury or occurring indirectly to compensate for underlying problems include abnormal muscle tone; weakness and lack of fitness; limited variety of muscle synergies; contracture and altered biomechanics, the net result being limited functional ability. Other contributors to the motor disorder include sensory, cognitive and perceptual impairments. In recent years understanding of the motor problem has increased, but less is known about effects of therapy. Evidence suggests that therapy can improve functional possibilities for children with cerebral palsy but is inconclusive as to which approach might be most beneficial. The therapist requires an understanding of the interaction of all systems, cognitive/perceptual, motor, musculoskeletal, sensory and behavioral, in the context of the development and plasticity of the CNS. It is necessary to understand the limitations of the damaged immature nervous system, but important to optimize the child's functional possibilities. PMID:11530888

Effects of whole body vibration on muscle spasticity for people with central nervous system disorders: a systematic review.

PubMed

Huang, Meizhen; Liao, Lin-Rong; Pang, Marco Yc

2017-01-01

To examine the effects of whole-body vibration on spasticity among people with central nervous system disorders. Electronic searches were conducted using CINAHL, Cochrane Library, MEDLINE, Physiotherapy Evidence Database, PubMed, PsycINFO, SPORTDiscus and Scopus to identify randomized controlled trials that investigated the effect of whole-body vibration on spasticity among people with central nervous system disorders (last search in August 2015). The methodological quality and level of evidence were rated using the PEDro scale and guidelines set by the Oxford Centre for Evidence-Based Medicine. Nine trials with totally 266 subjects (three in cerebral palsy, one in multiple sclerosis, one in spinocerebellar ataxia, and four in stroke) fulfilled all selection criteria. One study was level 1b (PEDro⩾6 and sample size>50) and eight were level 2b (PEDro<6 or sample size ⩽50). All three cerebral palsy trials (level 2b) reported some beneficial effects of whole-body vibration on reducing leg muscle spasticity. Otherwise, the results revealed no consistent benefits on spasticity in other neurological conditions studied. There is little evidence that change in spasticity was related to change in functional performance. The optimal protocol could not be identified. Many reviewed studies were limited by weak methodological and reporting quality. Adverse events were minor and rare. Whole-body vibration may be useful in reducing leg muscle spasticity in cerebral palsy but this needs to be verified by future high quality trials. There is insufficient evidence to support or refute the notion that whole-body vibration can reduce spasticity in stroke, spinocerebellar ataxia or multiple sclerosis.

Mobile communication jacket for people with severe speech impairment.

PubMed

Lampe, Renée; Blumenstein, Tobias; Turova, Varvara; Alves-Pinto, Ana

2018-04-01

Cerebral palsy is a movement disorder caused by damage to motor control areas of the developing brain during early childhood. Motor disorders can also affect the ability to produce clear speech and to communicate. The aim of this study was to develop and to test a prototype of an assistive tool with an embedded mobile communication device to support patients with severe speech impairments. A prototype was developed by equipping a cycling jacket with a display, a small keyboard, a LED and an alarm system, all controlled by a microcontroller. Functionality of the prototype was tested in six participants (aged 7-20 years) with cerebral palsy and global developmental disorder and three healthy persons. A patient questionnaire consisting of seven items was used as an evaluation tool. A working prototype of the communication jacket was developed and tested. The questionnaire elicited positive responses from participants. Improvements to correct revealed weaknesses were proposed. Enhancements like voice output of pre-selected phrases and enlarged display were implemented. Integration in a jacket makes the system mobile and continuously available to the user. The communication jacket may be of great benefit to patients with motor and speech impairments. Implications for Rehabilitation The communication jacket developed can be easily used by people with movement and speech impairment. All technical components are integrated in a garment and do not have to be held with the hands or transported separately. The system is adaptable to individual use. Both expected and unexpected events can be dealt with, which contributes to the quality of life and self-fulfilment.

False positives in psychiatric diagnosis: implications for human freedom.

PubMed

Wakefield, Jerome C

2010-02-01

Current symptom-based DSM and ICD diagnostic criteria for mental disorders are prone to yielding false positives because they ignore the context of symptoms. This is often seen as a benign flaw because problems of living and emotional suffering, even if not true disorders, may benefit from support and treatment. However, diagnosis of a disorder in our society has many ramifications not only for treatment choice but for broader social reactions to the diagnosed individual. In particular, mental disorders impose a sick role on individuals and place a burden upon them to change; thus, disorders decrease the level of respect and acceptance generally accorded to those with even annoying normal variations in traits and features. Thus, minimizing false positives is important to a pluralistic society. The harmful dysfunction analysis of disorder is used to diagnose the sources of likely false positives, and propose potential remedies to the current weaknesses in the validity of diagnostic criteria.

Further understanding of complex information processing in verbal adolescents and adults with autism spectrum disorders.

PubMed

Williams, Diane L; Minshew, Nancy J; Goldstein, Gerald

2015-10-01

More than 20 years ago, Minshew and colleagues proposed the Complex Information Processing model of autism in which the impairment is characterized as a generalized deficit involving multiple modalities and cognitive domains that depend on distributed cortical systems responsible for higher order abilities. Subsequent behavioral work revealed a related dissociation between concept formation and concept identification in autism suggesting the lack of an underlying organizational structure to manage increases in processing loads. The results of a recent study supported the impact of this relative weakness in conceptual reasoning on adaptive functioning in children and adults with autism. In this study, we provide further evidence of the difficulty relatively able older adolescents and adults with autism have with conceptual reasoning and provide evidence that this characterizes their difference from age- and ability-matched controls with typical development better than their differences in language. For verbal adults with autism, language may serve as a bootstrap or compensatory mechanism for learning but cannot overcome an inherent weakness in concept formation that makes information processing challenging as task demands increase. © The Author(s) 2015.

Management of myasthenic crisis in a child.

PubMed

Rybojad, Beata; Lesiuk, Witold; Fijałkowska, Anna; Rybojad, Paweł; Sawicki, Marek; Lesiuk, Leszek

2013-01-01

Myasthenia gravis is an autoimmune disorder of peripheral nervous system, leading to fluctuating muscle weakness. It is caused by circulating antibodies that block acetylcholine nicotinic postsynaptic receptors at the postsynaptic neuromuscular junction. Myasthenic crisis is a life-threatening complication, which is defined as weakness from acquired myasthenia gravis. In this paper we described a 15-year-old boy who was admitted to the Paediatric Intensive Care Unit due to myasthenic crisis. He had suffered not only from myasthenia gravis but also hypothyroidism, cerebral palsy and epilepsy. The patient required mechanical ventilation and was successfully treated with both plasmapheresis and intravenous immunoglobulins. He recovered from the crisis and then thymectomy was performed. Perioperative period and anaesthesia passed uncomplicated. Discharged home from the hospital after 2.5 month-treatment, for the last 4 years, he has only come on scheduled outpatient medical appointments. This case reveals that myasthenic crisis, albeit rare, may occur in male adolescents. In such cases multidisciplinary care followed by surgery becomes a procedure of choice. Concomitant medical problems, if well controlled, do not affect the results of outcome of the underlying disease.

Hypoglycemia, hepatic dysfunction, muscle weakness, cardiomyopathy, free carnitine deficiency and long-chain acylcarnitine excess responsive to medium chain triglyceride diet.

PubMed

Glasgow, A M; Engel, A G; Bier, D M; Perry, L W; Dickie, M; Todaro, J; Brown, B I; Utter, M F

1983-05-01

Fraternal twins who had fasting hypoglycemia, hypoketonemia, muscle weakness, and hepatic dysfunction are reported. The hepatic dysfunction occurred only during periods of caloric deprivation. The surviving patient developed a cardiomyopathy. In this sibling, muscle weakness and cardiomyopathy were markedly improved by a diet high in medium chain triglycerides. There was a marked deficiency of muscle total carnitine and a mild deficiency of hepatic total carnitine. Unlike patients with systemic carnitine deficiency, serum and muscle long-chain acylcarnitine were elevated and renal reabsorption of carnitine was normal. It was postulated that the defect in long-chain fatty acid oxidation in this disorder is caused by an abnormality in the mitochondrial acylcarnitine transport. Detailed studies of the cause of the hypoglycemia revealed that insulin, growth hormone, cortisol, and glucagon secretion were appropriate and that it is unlikely that there was a major deficiency of a glycolytic or gluconeogenic enzyme. Glucose production and alanine conversion to glucose were in the low normal range when compared to normal children in the postabsorptive state. The hypoglycemia in our patients was probably due to a modest increase in glucose consumption, secondary to the decreased oxidation of fatty acids and ketones, alternate fuels which spare glucose utilization, plus a modest decrease in hepatic glucose production secondary to decreased available hepatic energy substrates.

[Anorexia nervosa in the light of neurocognitive functioning: New theoretical and therapeutic perspectives].

PubMed

Martinez, G; Cook-Darzens, S; Chaste, P; Mouren, M-C; Doyen, C

2014-04-01

Anorexia nervosa is a serious psychiatric disorder, for which very few validated therapeutic strategies exist. The specific sociocognitive style of anorexic patients has already been described in the 1960s: it involves a concrete style with abstraction difficulties. Current neuropsychological tests have contributed to a more precise definition of these difficulties. IS THERE A SPECIFIC COGNITIVE PROFILE?: Contrary to common beliefs, these patients' intellectual performances are not superior to those of the general population. However, detailed comparisons of profiles on the Weschler Scales suggest difficulties in synthesizing information and better abilities in concrete problem solving. The dominant hypothesis concerning the attentional dimension is the existence of a weakness in central coherence, resulting in superior detail processing and a weakness in global integration. This trend appears to be stable even after the normalization of nutritional status. The impairment of set-shifting abilities leads to rigidity, expressed by inflexibility and perseveration, both in reasoning and behaviour. This reduced cognitive flexibility appears to persist after recovery, and may constitute a familial trait. In addition, this likely endophenotype seems to be independent from obsessional traits. Alexithymia is frequently described in anorexic individuals. It is the verbal description of feelings which seems to be particularly impaired. It may explain underlying difficulties in empathy. Indeed, these subjects have lower scores on emotional tests drawn from the theory of mind. These cognitive abnormalities are well documented in pervasive developmental disorders. NEUROANATOMICAL DATA: NEUROIMAGING IN SUPPORT OF LIMBIC AND FRONTO-STRIATAL ABNORMALITIES: Evidence from neuroimaging suggests abnormalities in cortical and subcortical structures, involving the temporal and orbito-frontal lobes. Various functional hypotheses are formulated, involving fronto-striatothalamic circuits, amygdala or insula. IS ANOREXIA NERVOSA A DEVELOPMENTAL DISORDER?: Pervasive developmental disorders are over-represented among anorexic subjects in comparison to the general population. Conversely, restrictive and selective eating disorders are more frequent among individuals presenting an autistic spectrum disorder. In view of the common cognitive and neuroanatomical data that are found in anorexia nervosa and neurodevelopmental disorders, we adhere to the hypothesis that anorexia nervosa may be similar to a neurodevelopmental disorder. Clinical observations suggest that this hypothesis may be especially relevant in the early forms of anorexia nervosa. These cognitive data confirm the potential relevance of new therapeutic modalities such as cognitive remediation. Initial results from its application to anorexia nervosa seem promising. A review of the recent literature highlights the possible existence of a developmental impairment of cortical and subcortical structures, associated with specific abnormalities in cognitive development such as a weakness in central coherence, reduced set-shifting ability and poor social skills. On this basis, cognitive remediation may be a promising therapeutic innovation. Copyright © 2013. Published by Elsevier Masson SAS.

Protean manifestations of vitamin D deficiency, part 3: association with cardiovascular disease and disorders of the central and peripheral nervous systems.

PubMed

Bell, David S H

2011-05-01

Vitamin D deficiency is associated with the risk factors of inflammation, insulin resistance and endothelial dysfunction, and left ventricular hypertrophy. As a result there is an increase in cardiovascular events (CVEs) associated with vitamin D deficiency. Vitamin D deficiency itself or secondary hyperparathyroidism or both may be responsible for the increase in CVEs. Correction of vitamin D deficiency may decrease the incidence of CVEs. Vitamin D deficiency is also associated with Alzheimer disease, schizophrenia, depression, and chronic pain and muscle weakness. Vitamin D deficiency is early treated with oral vitamin D supplements which may improve the manifestations of the diseases associated with vitamin D deficiency.

Atom-Pair Kinetics with Strong Electric-Dipole Interactions.

PubMed

Thaicharoen, N; Gonçalves, L F; Raithel, G

2016-05-27

Rydberg-atom ensembles are switched from a weakly to a strongly interacting regime via adiabatic transformation of the atoms from an approximately nonpolar into a highly dipolar quantum state. The resultant electric dipole-dipole forces are probed using a device akin to a field ion microscope. Ion imaging and pair-correlation analysis reveal the kinetics of the interacting atoms. Dumbbell-shaped pair-correlation images demonstrate the anisotropy of the binary dipolar force. The dipolar C_{3} coefficient, derived from the time dependence of the images, agrees with the value calculated from the permanent electric-dipole moment of the atoms. The results indicate many-body dynamics akin to disorder-induced heating in strongly coupled particle systems.

Ehlers-Danlos Syndrome Type VI in a 17-Year-Old Iranian Boy with Severe Muscular Weakness – A Diagnostic Challenge?

PubMed Central

Kariminejad, Ariana; Bozorgmehr, Bita; Khatami, Alireza; Kariminejad, Mohamad-Hasan; Giunta, Cecilia; Steinmann, Beat

2010-01-01

Background The Ehlers-Danlos syndrome type VI (EDSVI) is an autosomal recessive connective tissue disease which is characterized by severe hypotonia at birth, progressive kyphoscoliosis, skin hyperelasticity and fragility, joint hypermobility and (sub-)luxations, microcornea, rupture of arteries and the eye globe, and osteopenia. The enzyme collagen lysyl hydroxylase (LH1) is deficient in these patients due to mutations in the PLOD1 gene. Case Presentation We report a 17-year-old boy, born to related parents, with severe kyphoscoliosis, scar formation, joint hypermobility and multiple dislocations, muscular weakness, rupture of an ocular globe, and a history of severe infantile hypotonia. EDS VI was suspected clinically and confirmed by an elevated ratio of urinary total lysyl pyridinoline to hydroxylysyl pyridinoline, abnormal electrophoretic mobility of the α-collagen chains, and mutation analysis. Conclusion Because of the high rate of consanguineous marriages in Iran and, as a consequence thereof, an increased rate of autosomal recessive disorders, we urge physicians to consider EDS VI in the differential diagnosis of severe infantile hypotonia and muscular weakness, a disorder which can easily be confirmed by the analysis of urinary pyridinolines that is highly specific, sensitive, robust, fast, non-invasive, and inexpensive. PMID:23056730

Na(23)K(9)Tl(15.3): An Unusual Zintl Compound Containing Apparent Tl(5)(7)(-), Tl(4)(8)(-), Tl(3)(7)(-), and Tl(5)(-) Anions.

PubMed

Dong, Zhen-Chao; Corbett, John D.

1996-05-22

Reaction of the neat elements in tantalum containers at 400 degrees C and then 150 degrees C gives the pure title phase. X-ray crystallography shows that the hexagonal structure (P6(3)/mmc, Z = 2, a = 11.235(1) Å, b = 30.133(5) Å) contains relatively high symmetry clusters Tl(5)(7)(-) (D(3)(h)()), Tl(4)(8)(-) (C(3)(v)(), approximately T(d)), and the new Tl(3)(7)(-) (D(infinity)(h)()) plus Tl(5)(-), the last two disordered over the same elongated site in 1:2 proportions. Cation solvation of these anions is tight and specific, providing good Coulombic trapping of weakly bound electrons on the isolated cluster anions. The observed disorder makes the compound structurally a Zintl phase with a closed shell electron count. EHMO calculations on the novel Tl(3)(7)(-) reveal some bonding similarities with the isoelectronic CO(2), with two good sigma(s,p) bonding and two weakly bonding pi MO's. The Tl-Tl bond lengths therein (3.14 Å) are evidently consistent with multiple bonding. The weak temperature-independent paramagnetism and metallic conductivity (rho(293) approximately 90 &mgr;Omega.cm) of the phase are discussed.

Wechsler Intelligence Scale for Children 4th edition-Chinese version index scores in Taiwanese children with attention-deficit/hyperactivity disorder.

PubMed

Yang, Pinchen; Cheng, Chung-Ping; Chang, Chen-Lin; Liu, Tai-Ling; Hsu, Hsiu-Yi; Yen, Cheng-Fang

2013-02-01

The Wechsler Intelligence Scale for Children 4th edition-Chinese version (WISC-IV-Chinese) has been in clinical use in Taiwan since 2007. Research is needed to determine how the WISC-IV, modified from its earlier version, will affect its interpretation in clinical practice in a Mandarin-speaking context. We attempted to use WISC-IV-Chinese scores to identify the cognitive strengths and weaknesses in 334 Taiwanese children with attention-deficit/hyperactivity disorder (ADHD). Comparison of cognitive profiles of WISC-IV-Chinese scores between subtypes of ADHD was also performed. The results indicated that the four-factor model of the WISC-IV-Chinese fitted well for Taiwanese children with ADHD. The profiles showed that performance in the index score of the Processing Speed Index was the weakness domain for the Taiwanese children with ADHD, as confirmed by two different kinds of analytic methods. Cognitive profile analysis of ADHD subtypes revealed children with inattentive subtypes to have a greater weakness in processing speed performance. The implications of the profiles of the index scores on the WISC-IV-Chinese version for Taiwanese children with ADHD were explored. © 2013 The Authors. Psychiatry and Clinical Neurosciences © 2013 Japanese Society of Psychiatry and Neurology.

Paraneoplastic Neuromyelitis Optica Spectrum Disorder Associated With Metastatic Carcinoid Expressing Aquaporin-4

PubMed Central

Figueroa, Michelle; Guo, Yong; Tselis, Alexandros; Pittock, Sean J.; Lennon, Vanda A.; Lucchinetti, Claudia F.; Lisak, Robert P.

2014-01-01

IMPORTANCE Reports of neuromyelitis optica spectrum disorder (NMOSD) occurring in the setting of neoplasia suggest that aquaporin-4 autoimmunitymay in some cases have a paraneoplastic basis. OBSERVATIONS In this case report, we describe a patient with NMOSD whose test results were seropositive for aquaporin-4 IgG and who had a hepatic metastasis from a small-bowel neuroendocrine tumor. The tumor cells expressed aquaporin-4 immunoreactivity. She presented to the Neurology Department at Wayne State University with bilateral leg weakness, ascending paresthesias, and decreased sensation. CONCLUSIONS AND RELEVANCE This case extends the context of NMOSD as a paraneoplastic disorder. PMID:24733266

Music therapy and music medicine for children and adolescents.

PubMed

Yinger, Olivia Swedberg; Gooding, Lori

2014-07-01

This article summarizes the research on music therapy and music medicine for children and adolescents with diagnoses commonly treated by psychiatrists. Music therapy and music medicine are defined, effects of music on the brain are described, and music therapy research in psychiatric treatment is discussed. Music therapy research with specific child/adolescent populations is summarized, including disorders usually diagnosed in childhood, substance abuse, mood/anxiety disorders, and eating disorders. Clinical implications are listed, including suggestions for health care professionals seeking to use music medicine techniques. Strengths and weaknesses of music therapy treatment are discussed, as well as areas for future research. Published by Elsevier Inc.

Fatigue is associated with muscle weakness in Ehlers-Danlos syndrome: an explorative study.

PubMed

Voermans, N C; Knoop, H; Bleijenberg, G; van Engelen, B G

2011-06-01

Ehlers-Danlos syndrome (EDS) is a clinically and genetically heterogeneous group of inherited connective tissue disorders characterised by joint hypermobility, skin hyperextensibility and tissue fragility. It has recently been shown that muscle weakness occurs frequently in EDS, and that fatigue is a common and clinically important symptom. The aim of this study was to investigate the relationship between fatigue severity and subjective and objective measures of muscle weakness. Furthermore, the predictive value of muscle weakness for fatigue severity was determined, together with that of pain and physical activity. An explorative, cross-sectional, observational study. Thirty EDS patients, recruited from the Dutch patient association, were investigated at the neuromuscular outpatient department of a tertiary referral centre in The Netherlands. Muscle strength measured with manual muscle strength testing and hand-held dynamometry. Self-reported muscle weakness, pain, physical activity levels and fatigue were assessed with standardised questionnaires. Fatigue severity in EDS was significantly correlated with measured and self-reported muscle weakness (r=-0.408 for manual muscle strength, r=0.461 for hand-held dynamometry and r=0.603 for self-reported muscle weakness). Both muscle weakness and pain severity were significant predictors of fatigue severity in a multiple regression analysis. The results suggest a positive and direct relationship between fatigue severity and muscle weakness in EDS. Future research should focus on the relationship between fatigue, muscle weakness and objectively measured physical activity, preferably in a larger cohort of EDS patients. Copyright © 2010 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Monitoring Reasons for Encounter via an Electronic Patient Record System: the Case of a Rural Practice Initiative

PubMed Central

Klinis, Spyridon; Markaki, Adelais; Kounalakis, Dimitrios; Symvoulakis, Emmanouil K.

2012-01-01

The objective of this brief communication was to tabulate common reasons for encounter in a Greek rural general practice, as result of a recently adopted electronic patient record (EPR) application. Twenty encounter reasons accounted for 3,797 visits (61% of all patient encounters), whereas 565 other reasons accounted for the remaining 2,429 visits (39%). Number one reason for encounter was health maintenance or disease prevention seeking services, including screening examinations for malignancies, immunization and provision of medical opinion reports. Hypertension, lipid disorder and ischemic heart disease without angina were among the most common reasons for seeking care. A strengths/weaknesses/opportunities/threats (SWOT) analysis on the key role of an EPR system in collecting data from rural and remote primary health care settings is also presented. PMID:23091407

Dynamic Nuclear Polarization and the Paradox of Quantum Thermalization.

PubMed

De Luca, Andrea; Rosso, Alberto

2015-08-21

Dynamic nuclear polarization (DNP) is to date the most effective technique to increase the nuclear polarization opening disruptive perspectives for medical applications. In a DNP setting, the interacting spin system is quasi-isolated and brought out of equilibrium by microwave irradiation. Here we show that the resulting stationary state strongly depends on the ergodicity properties of the spin many-body eigenstates. In particular, the dipolar interactions compete with the disorder induced by local magnetic fields resulting in two distinct dynamical phases: while for weak interaction, only a small enhancement of polarization is observed, for strong interactions the spins collectively equilibrate to an extremely low effective temperature that boosts DNP efficiency. We argue that these two phases are intimately related to the problem of thermalization in closed quantum systems where a many-body localization transition can occur varying the strength of the interactions.

Prominent subcutaneous oedema as a masquerading symptom of an underlying inflammatory myopathy.

PubMed

Anantharajah, Anthea; Vucic, Steve; Tarafdar, Surjit; Vongsuvanh, Roslyn; Wilcken, Nicholas; Swaminathan, Sanjay

2017-02-01

The inflammatory myopathies are a group of immune-mediated inflammatory muscle disorders that typically present with marked proximal muscle weakness. We report four cases of inflammatory myopathies with marked subcutaneous oedema as their main complaint. Three of the four patients had normal or low levels of creatine kinase, an enzyme often markedly elevated in these disorders. Magnetic resonance imaging of the muscles, followed by a muscle biopsy were used to make a definitive diagnosis. © 2017 Royal Australasian College of Physicians.

Autosomal recessive type II hereditary motor and sensory neuropathy with acrodystrophy.

PubMed

Thomas, P K; Claus, D; King, R H

1999-02-01

A family is described with presumed autosomal recessive inheritance in which three siblings developed a progressive neuropathy that combined limb weakness and severe distal sensory loss leading to prominent mutilating changes. Electrophysiological and nerve biopsy findings indicated an axonopathy. The disorder is therefore classifiable as type II hereditary motor and sensory neuropathy (HMSN II). The clinical features differ from those reported in previously described cases of autosomal recessive HMSN II. This disorder may therefore represent a new variant.

Theory of disordered unconventional superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keles, A.; Andreev, A. V.; Spivak, B. Z., E-mail: spivak@uw.edu

In contrast to conventional s-wave superconductivity, unconventional (e.g., p- or d-wave) superconductivity is strongly suppressed even by relatively weak disorder. Upon approaching the superconductormetal transition, the order parameter amplitude becomes increasingly inhomogeneous, leading to effective granularity and a phase ordering transition described by the Mattis model of spin glasses. One consequence of this is that at sufficiently low temperatures, between the clean unconventional superconducting and the diffusive metallic phases, there is necessarily an intermediate superconducting phase that exhibits s-wave symmetry on macroscopic scales.

Spectral diffusion in poly(para-phenylene)-type polymers with different energetic disorder

NASA Astrophysics Data System (ADS)

Hoffmann, Sebastian T.; Bässler, Heinz; Koenen, Jan-Moritz; Forster, Michael; Scherf, Ullrich; Scheler, Esther; Strohriegl, Peter; Köhler, Anna

2010-03-01

We have employed quasicontinuous fluorescence and phosphorescence spectroscopy within a temperature range between 10 and 500 K to monitor the spectral diffusion of singlet and triplet excitons in a series of π -conjugated polymers. We investigated (i) how spectral diffusion is controlled by the degree of energetic disorder present in the amorphous film (that is reflected by the inhomogeneous broadening of the photoluminescence spectra) and (ii) how this process depends on the range of the electronic coupling (by comparing singlet exciton diffusion via long-range Förster transfer against triplet exciton diffusion by short-range Dexter transfer). For singlets, we find that the fluorescence spectra bear out a bathochromic shift upon cooling the sample down to a critical temperature below which the shift saturates. This bathochromic shift is a signature of spectral relaxation. Random-walk theory applied to excitation transport within a Gaussian density-of-states distribution is both necessary and sufficient to rationalize the experimental results in a quantitative fashion. The same behavior is observed for triplets in weakly disordered systems, such as in a polymer containing platinum in the main chain and a ladder-type polyphenylene. In contrast we observe a hypsochromic shift of the phosphorescence spectra below a characteristic temperature for triplets in systems with at least moderate energetic disorder. The hypsochromic shift proves that triplet exciton relaxation becomes frustrated because thermally activated exciton jumps that otherwise promote spectral diffusion become progressively frozen out. The frustration effect is controlled by the jump distance and thus it is specific for triplet excitations that migrate via short-range coupling among strongly localized states as compared to singlet excitons.

[Rehabilitation for musculoskeltal disorders in geriatric patients].

PubMed

Shirado, O

1997-07-01

Aging is typically accompanied by gradual but progressive physiological changes and an increased prevalence of acute and chronic illness in any organs. Musculoskeltal system is one of the most involved organs in geriatric patients. Appropriate roles in geriatric rehabilitation for musculoskeltal disorders should be emphasized not only to treat the disorders, but also to prevent many complications cause by specific disease or injury. Representative management methods in geriatric rehabilitation are introduced in this section. Rest is often effective, especially in the acute phase of illness or injury. However, cautions should be paid in disuse syndrome which may be produced by prolonged bed rest. Major manifestations in this syndrome includes muscle weakness and atrophy, joint contracture, decubitus, osteoporosis, ectopic ossification, cardiovascular impairment, pneumonia, urological and mental problems. Physical agents such as heat, cold, light and pressure have been used as therapeutic agents. Electrical stimulation is often effective in the treatment of low-back pain syndrome. Traction is the act of drawing, or a pulling force. Its mechanism to relieve pain seems to immobilize the injured parts, to increase peripheral circulation by massage effect and to improve muscle spasm. Brace is very effective to control acute pain in musculoskeltal system. However, long-term wear of brace should be avoided to prevent the disuse syndrome. Exercise is one of the most important rehabilitation modalities. This includes stretching and muscle strengthening programs. Education of body mechanism in activity of daily living is essential in rehabilitation of geriatric patients.

Comprehensive Assessment of Children and Youth with ADHD.

ERIC Educational Resources Information Center

Burcham, Barbara G.; DeMers, Stephen T.

1995-01-01

Principles of comprehensive assessment of students with attention deficit hyperactivity disorder are examined in relation to legal compliance, special considerations for cultural diversity, medical diagnosis versus educational identification, and the problem-solving assessment model. Strengths and weakness of specific strategies are identified as…

Current Trends in the Treament of Phobias in Autistic and Mentally Retarded Persons.

ERIC Educational Resources Information Center

Jackson, Henry J.

1983-01-01

The paper reviews research on phobic disorders of mentally retarded and autistic persons, noting the definitions, incidence and prevalence, etiological explanations, and treatment approaches. Methodological weaknesses are stressed. Behavioral interventions are seen as the treatments of choice. (CL)

Weak measurements and quantum weak values for NOON states

NASA Astrophysics Data System (ADS)

Rosales-Zárate, L.; Opanchuk, B.; Reid, M. D.

2018-03-01

Quantum weak values arise when the mean outcome of a weak measurement made on certain preselected and postselected quantum systems goes beyond the eigenvalue range for a quantum observable. Here, we propose how to determine quantum weak values for superpositions of states with a macroscopically or mesoscopically distinct mode number, that might be realized as two-mode Bose-Einstein condensate or photonic NOON states. Specifically, we give a model for a weak measurement of the Schwinger spin of a two-mode NOON state, for arbitrary N . The weak measurement arises from a nondestructive measurement of the two-mode occupation number difference, which for atomic NOON states might be realized via phase contrast imaging and the ac Stark effect using an optical meter prepared in a coherent state. The meter-system coupling results in an entangled cat-state. By subsequently evolving the system under the action of a nonlinear Josephson Hamiltonian, we show how postselection leads to quantum weak values, for arbitrary N . Since the weak measurement can be shown to be minimally invasive, the weak values provide a useful strategy for a Leggett-Garg test of N -scopic realism.

Stigmatising attitudes towards people with mental disorders: a comparison of Australian health professionals with the general community.

PubMed

Reavley, Nicola J; Mackinnon, Andrew J; Morgan, Amy J; Jorm, Anthony F

2014-05-01

The aim of this paper was to explore attitudes towards people with mental disorders among Australian health professionals (psychiatrists, psychologists and general practitioners (GPs)) and to compare their attitudes with members of the general community. The study involved a postal survey of 518 GPs, 506 psychiatrists and 498 clinical psychologists and a telephone survey of 6019 members of the general community. Participants were given a case vignette describing a person with either depression, depression with suicidal thoughts, early schizophrenia, chronic schizophrenia, post-traumatic stress disorder (PTSD) or social phobia and two questionnaires to assess stigmatising attitudes (the Depression Stigma Scale and the Social Distance Scale). Exploratory structural equation modelling was used to elucidate the structure of stigma as measured by the two scales, to establish dimensions of stigma and to compare patterns of association according to gender, age, vignette and professional grouping. The measurement characteristics of stigmatising attitudes in health professionals were found to be comparable to those in members of the general community in social distance and also in personal and perceived attitude stigma, with each forming distinct dimensions and each comprising 'Weak-not-sick' and 'Dangerous/unpredictable' components. Among health professionals, female gender, age and being a GP were associated with higher scores on the personal stigma scales. Mental health professionals had lower scores on the personal 'Weak-not-sick' and 'Dangerous/unpredictable' scales than members of the general community, while there were no significant differences in the desire for social distance between health professionals and the general community. While mental health professionals have less stigmatising attitudes than the general public, the greater beliefs in dangerousness and personal weakness by GPs should be addressed.

Structural Stability of Mathematical Models of National Economy

NASA Astrophysics Data System (ADS)

Ashimov, Abdykappar A.; Sultanov, Bahyt T.; Borovskiy, Yuriy V.; Adilov, Zheksenbek M.; Ashimov, Askar A.

2011-12-01

In the paper we test robustness of particular dynamic systems in a compact regions of a plane and a weak structural stability of one dynamic system of high order in a compact region of its phase space. The test was carried out based on the fundamental theory of dynamical systems on a plane and based on the conditions for weak structural stability of high order dynamic systems. A numerical algorithm for testing the weak structural stability of high order dynamic systems has been proposed. Based on this algorithm we assess the weak structural stability of one computable general equilibrium model.

Role of Orbital Dynamics in Spin Relaxation and Weak Antilocalization in Quantum Dots

NASA Astrophysics Data System (ADS)

Zaitsev, Oleg; Frustaglia, Diego; Richter, Klaus

2005-01-01

We develop a semiclassical theory for spin-dependent quantum transport to describe weak (anti)localization in quantum dots with spin-orbit coupling. This allows us to distinguish different types of spin relaxation in systems with chaotic, regular, and diffusive orbital classical dynamics. We find, in particular, that for typical Rashba spin-orbit coupling strengths, integrable ballistic systems can exhibit weak localization, while corresponding chaotic systems show weak antilocalization. We further calculate the magnetoconductance and analyze how the weak antilocalization is suppressed with decreasing quantum dot size and increasing additional in-plane magnetic field.

Stochastic simulation of reaction-diffusion systems: A fluctuating-hydrodynamics approach

NASA Astrophysics Data System (ADS)

Kim, Changho; Nonaka, Andy; Bell, John B.; Garcia, Alejandro L.; Donev, Aleksandar

2017-03-01

We develop numerical methods for stochastic reaction-diffusion systems based on approaches used for fluctuating hydrodynamics (FHD). For hydrodynamic systems, the FHD formulation is formally described by stochastic partial differential equations (SPDEs). In the reaction-diffusion systems we consider, our model becomes similar to the reaction-diffusion master equation (RDME) description when our SPDEs are spatially discretized and reactions are modeled as a source term having Poisson fluctuations. However, unlike the RDME, which becomes prohibitively expensive for an increasing number of molecules, our FHD-based description naturally extends from the regime where fluctuations are strong, i.e., each mesoscopic cell has few (reactive) molecules, to regimes with moderate or weak fluctuations, and ultimately to the deterministic limit. By treating diffusion implicitly, we avoid the severe restriction on time step size that limits all methods based on explicit treatments of diffusion and construct numerical methods that are more efficient than RDME methods, without compromising accuracy. Guided by an analysis of the accuracy of the distribution of steady-state fluctuations for the linearized reaction-diffusion model, we construct several two-stage (predictor-corrector) schemes, where diffusion is treated using a stochastic Crank-Nicolson method, and reactions are handled by the stochastic simulation algorithm of Gillespie or a weakly second-order tau leaping method. We find that an implicit midpoint tau leaping scheme attains second-order weak accuracy in the linearized setting and gives an accurate and stable structure factor for a time step size of an order of magnitude larger than the hopping time scale of diffusing molecules. We study the numerical accuracy of our methods for the Schlögl reaction-diffusion model both in and out of thermodynamic equilibrium. We demonstrate and quantify the importance of thermodynamic fluctuations to the formation of a two-dimensional Turing-like pattern and examine the effect of fluctuations on three-dimensional chemical front propagation. By comparing stochastic simulations to deterministic reaction-diffusion simulations, we show that fluctuations accelerate pattern formation in spatially homogeneous systems and lead to a qualitatively different disordered pattern behind a traveling wave.

Stochastic simulation of reaction-diffusion systems: A fluctuating-hydrodynamics approach

DOE PAGES

Kim, Changho; Nonaka, Andy; Bell, John B.; ...

2017-03-24

Here, we develop numerical methods for stochastic reaction-diffusion systems based on approaches used for fluctuating hydrodynamics (FHD). For hydrodynamic systems, the FHD formulation is formally described by stochastic partial differential equations (SPDEs). In the reaction-diffusion systems we consider, our model becomes similar to the reaction-diffusion master equation (RDME) description when our SPDEs are spatially discretized and reactions are modeled as a source term having Poisson fluctuations. However, unlike the RDME, which becomes prohibitively expensive for an increasing number of molecules, our FHD-based description naturally extends from the regime where fluctuations are strong, i.e., each mesoscopic cell has few (reactive) molecules,more » to regimes with moderate or weak fluctuations, and ultimately to the deterministic limit. By treating diffusion implicitly, we avoid the severe restriction on time step size that limits all methods based on explicit treatments of diffusion and construct numerical methods that are more efficient than RDME methods, without compromising accuracy. Guided by an analysis of the accuracy of the distribution of steady-state fluctuations for the linearized reaction-diffusion model, we construct several two-stage (predictor-corrector) schemes, where diffusion is treated using a stochastic Crank-Nicolson method, and reactions are handled by the stochastic simulation algorithm of Gillespie or a weakly second-order tau leaping method. We find that an implicit midpoint tau leaping scheme attains second-order weak accuracy in the linearized setting and gives an accurate and stable structure factor for a time step size of an order of magnitude larger than the hopping time scale of diffusing molecules. We study the numerical accuracy of our methods for the Schlögl reaction-diffusion model both in and out of thermodynamic equilibrium. We demonstrate and quantify the importance of thermodynamic fluctuations to the formation of a two-dimensional Turing-like pattern and examine the effect of fluctuations on three-dimensional chemical front propagation. Furthermore, by comparing stochastic simulations to deterministic reaction-diffusion simulations, we show that fluctuations accelerate pattern formation in spatially homogeneous systems and lead to a qualitatively different disordered pattern behind a traveling wave.« less

Stereotypic Behavior in Nonhuman Primates as a Model for the Human Condition

PubMed Central

Lutz, Corrine K.

2014-01-01

Stereotypies that develop spontaneously in nonhuman primates can provide an effective model for repetitive stereotyped behavior in people with neurodevelopmental or obsessive-compulsive disorders. The behaviors are similar in form, are similarly affected by environmental conditions, and are improved with similar treatment methods such as enrichment, training, and drug therapy. However, because of a greater number of commonalities in these factors, nonhuman primates may serve as a better model for stereotyped behavior in individuals with autism or intellectual disability than for compulsions in individuals with obsessive-compulsive disorder. Because animal models may not be exact in all features of the disorder being studied, it is important to investigate the strengths and weaknesses of using a nonhuman primate model for stereotyped behavior in people with psychological disorders. PMID:25225307

Optical perturbation of atoms in weak localization

NASA Astrophysics Data System (ADS)

Yedjour, A.

2018-01-01

We determine the microscopic transport parameters that are necessary to describe the diffusion process of the atomic gas in optical speckle. We use the self-consistent theory to calculate the self-energy of the atomic gas. We compute the spectral function numerically by an average over disorder realizations in terms of the Greens function. We focus mainly on the behaviour of the energy distribution of the atoms to estimate a correction to the mobility edge. Our results show that the energy distribution of the atoms locates the mobility edge position under the disorder amplitude. This behaviour changes for each disorder parameter. We conclude that the disorder amplitude potential induced modification of the energy distribution of the atoms that plays a major role for the prediction of the mobility edge.

Retrospective natural history of thymidine kinase 2 deficiency.

PubMed

Garone, Caterina; Taylor, Robert W; Nascimento, Andrés; Poulton, Joanna; Fratter, Carl; Domínguez-González, Cristina; Evans, Julie C; Loos, Mariana; Isohanni, Pirjo; Suomalainen, Anu; Ram, Dipak; Hughes, M Imelda; McFarland, Robert; Barca, Emanuele; Lopez Gomez, Carlos; Jayawant, Sandeep; Thomas, Neil D; Manzur, Adnan Y; Kleinsteuber, Karin; Martin, Miguel A; Kerr, Timothy; Gorman, Grainne S; Sommerville, Ewen W; Chinnery, Patrick F; Hofer, Monika; Karch, Christoph; Ralph, Jeffrey; Cámara, Yolanda; Madruga-Garrido, Marcos; Domínguez-Carral, Jana; Ortez, Carlos; Emperador, Sonia; Montoya, Julio; Chakrapani, Anupam; Kriger, Joshua F; Schoenaker, Robert; Levin, Bruce; Thompson, John L P; Long, Yuelin; Rahman, Shamima; Donati, Maria Alice; DiMauro, Salvatore; Hirano, Michio

2018-03-30

Thymine kinase 2 (TK2) is a mitochondrial matrix protein encoded in nuclear DNA and phosphorylates the pyrimidine nucleosides: thymidine and deoxycytidine. Autosomal recessive TK2 mutations cause a spectrum of disease from infantile onset to adult onset manifesting primarily as myopathy. To perform a retrospective natural history study of a large cohort of patients with TK2 deficiency. The study was conducted by 42 investigators across 31 academic medical centres. We identified 92 patients with genetically confirmed diagnoses of TK2 deficiency: 67 from literature review and 25 unreported cases. Based on clinical and molecular genetics findings, we recognised three phenotypes with divergent survival: (1) infantile-onset myopathy (42.4%) with severe mitochondrial DNA (mtDNA) depletion, frequent neurological involvement and rapid progression to early mortality (median post-onset survival (POS) 1.00, CI 0.58 to 2.33 years); (2) childhood-onset myopathy (40.2%) with mtDNA depletion, moderate-to-severe progression of generalised weakness and median POS at least 13 years; and (3) late-onset myopathy (17.4%) with mild limb weakness at onset and slow progression to respiratory insufficiency with median POS of 23 years. Ophthalmoparesis and facial weakness are frequent in adults. Muscle biopsies show multiple mtDNA deletions often with mtDNA depletion. In TK2 deficiency, age at onset, rate of weakness progression and POS are important variables that define three clinical subtypes. Nervous system involvement often complicates the clinical course of the infantile-onset form while extraocular muscle and facial involvement are characteristic of the late-onset form. Our observations provide essential information for planning future clinical trials in this disorder. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Physiology of respiratory disturbances in muscular dystrophies

PubMed Central

Lo Mauro, Antonella

2016-01-01

Muscular dystrophy is a group of inherited myopathies characterised by progressive skeletal muscle wasting, including of the respiratory muscles. Respiratory failure, i.e. when the respiratory system fails in its gas exchange functions, is a common feature in muscular dystrophy, being the main cause of death, and it is a consequence of lung failure, pump failure or a combination of the two. The former is due to recurrent aspiration, the latter to progressive weakness of respiratory muscles and an increase in the load against which they must contract. In fact, both the resistive and elastic components of the work of breathing increase due to airway obstruction and chest wall and lung stiffening, respectively. The respiratory disturbances in muscular dystrophy are restrictive pulmonary function, hypoventilation, altered thoracoabdominal pattern, hypercapnia, dyspnoea, impaired regulation of breathing, inefficient cough and sleep disordered breathing. They can be present at different rates according to the type of muscular dystrophy and its progression, leading to different onset of each symptom, prognosis and degree of respiratory involvement. Key points A common feature of muscular dystrophy is respiratory failure, i.e. the inability of the respiratory system to provide proper oxygenation and carbon dioxide elimination. In the lung, respiratory failure is caused by recurrent aspiration, and leads to hypoxaemia and hypercarbia. Ventilatory failure in muscular dystrophy is caused by increased respiratory load and respiratory muscles weakness. Respiratory load increases in muscular dystrophy because scoliosis makes chest wall compliance decrease, atelectasis and fibrosis make lung compliance decrease, and airway obstruction makes airway resistance increase. The consequences of respiratory pump failure are restrictive pulmonary function, hypoventilation, altered thoracoabdominal pattern, hypercapnia, dyspnoea, impaired regulation of breathing, inefficient cough and sleep disordered breathing. Educational aims To understand the mechanisms leading to respiratory disturbances in patients with muscular dystrophy. To understand the impact of respiratory disturbances in patients with muscular dystrophy. To provide a brief description of the main forms of muscular dystrophy with their respiratory implications. PMID:28210319

Physiology of respiratory disturbances in muscular dystrophies.

PubMed

Lo Mauro, Antonella; Aliverti, Andrea

2016-12-01

Muscular dystrophy is a group of inherited myopathies characterised by progressive skeletal muscle wasting, including of the respiratory muscles. Respiratory failure, i.e . when the respiratory system fails in its gas exchange functions, is a common feature in muscular dystrophy, being the main cause of death, and it is a consequence of lung failure, pump failure or a combination of the two. The former is due to recurrent aspiration, the latter to progressive weakness of respiratory muscles and an increase in the load against which they must contract. In fact, both the resistive and elastic components of the work of breathing increase due to airway obstruction and chest wall and lung stiffening, respectively. The respiratory disturbances in muscular dystrophy are restrictive pulmonary function, hypoventilation, altered thoracoabdominal pattern, hypercapnia, dyspnoea, impaired regulation of breathing, inefficient cough and sleep disordered breathing. They can be present at different rates according to the type of muscular dystrophy and its progression, leading to different onset of each symptom, prognosis and degree of respiratory involvement. A common feature of muscular dystrophy is respiratory failure, i.e. the inability of the respiratory system to provide proper oxygenation and carbon dioxide elimination.In the lung, respiratory failure is caused by recurrent aspiration, and leads to hypoxaemia and hypercarbia.Ventilatory failure in muscular dystrophy is caused by increased respiratory load and respiratory muscles weakness.Respiratory load increases in muscular dystrophy because scoliosis makes chest wall compliance decrease, atelectasis and fibrosis make lung compliance decrease, and airway obstruction makes airway resistance increase.The consequences of respiratory pump failure are restrictive pulmonary function, hypoventilation, altered thoracoabdominal pattern, hypercapnia, dyspnoea, impaired regulation of breathing, inefficient cough and sleep disordered breathing. To understand the mechanisms leading to respiratory disturbances in patients with muscular dystrophy.To understand the impact of respiratory disturbances in patients with muscular dystrophy.To provide a brief description of the main forms of muscular dystrophy with their respiratory implications.

Adult celiac disease with acetylcholine receptor antibody positive myasthenia gravis

PubMed Central

Freeman, Hugh J; Gillett, Helen R; Gillett, Peter M; Oger, Joel

2009-01-01

Celiac disease has been associated with some autoimmune disorders. A 40-year-old competitive strongman with celiac disease responded to a gluten-free diet, but developed profound and generalized motor weakness with acetylcholine receptor antibody positive myasthenia gravis, a disorder reported to occur in about 1 in 5000. This possible relationship between myasthenia gravis and celiac disease was further explored in serological studies. Frozen stored serum samples from 23 acetylcholine receptor antibody positive myasthenia gravis patients with no intestinal symptoms were used to screen for celiac disease. Both endomysial and tissue transglutaminase antibodies were examined. One of 23 (or, about 4.3%) was positive for both IgA-endomysial and IgA tissue transglutaminase antibodies. Endoscopic studies subsequently showed duodenal mucosal scalloping and biopsies confirmed the histopathological changes of celiac disease. Celiac disease and myasthenia gravis may occur together more often than is currently appreciated. The presence of motor weakness in celiac disease may be a clue to occult myasthenia gravis, even in the absence of intestinal symptoms. PMID:19824105

Coherence and other autistic spectrum traits and eating disorders: building from mechanism to treatment. The Birgit Olsson lecture.

PubMed

Treasure, Janet

2013-02-01

To revisit Gillberg's hypothesis proposed in 1992, which was that anorexia nervosa should be considered within the spectrum of autistic disorders. A search was made of the literature relating to the behavioural traits, and cognitive, emotional and neuroanatomical intermediate phenotypes that are shared between autistic spectrum disorders (ASD) and anorexia nervosa. People with eating disorders in the acute phase (less so after recovery) share some behavioural traits (social impairment and restricted and repetitive behaviours) and intermediate phenotypes (weak central coherence, and impaired set shifting and theory of mind) with people in the autistic spectrum. Behavioural and intermediate neuropsychological traits are shared between eating disorders and ASD. In part, these are familial but also they are accentuated by the illness state and may be secondary to starvation. These traits have implications for prognosis and treatment.

Disorder dependence electron phonon scattering rate of V82Pd18 - xFex alloys at low temperature

NASA Astrophysics Data System (ADS)

Jana, R. N.; Meikap, A. K.

2018-04-01

We have systematically investigated the disorder dependence electron phonon scattering rate in three dimensional disordered V82Pd18 - xFex alloys. A minimum in temperature dependence resistivity curve has been observed at low temperature T =Tm. In the temperature range 5 K ≤ T ≤Tm the resistivity correction follows ρo 5 / 2T 1 / 2 law. The dephasing scattering time has been calculated from analysis of magnetoresistivity by weak localization theory. The electron dephasing time is dominated by electron-phonon scattering and follows anomalous temperature (T) and disorder (ρ0) dependence behaviour like τe-ph-1 ∝T2 /ρ0, where ρ0 is the impurity resistivity. The magnitude of the saturated dephasing scattering time (τ0) at zero temperature decreases with increasing disorder of the samples. Such anomalous behaviour of dephasing scattering rate is still unresolved.

Abortion and mental health disorders: evidence from a 30-year longitudinal study.

PubMed

Fergusson, David M; Horwood, L John; Boden, Joseph M

2008-12-01

Research on the links between abortion and mental health has been limited by design problems and relatively weak evidence. To examine the links between pregnancy outcomes and mental health outcomes. Data were gathered on the pregnancy and mental health history of a birth cohort of over 500 women studied to the age of 30. After adjustment for confounding, abortion was associated with a small increase in the risk of mental disorders; women who had had abortions had rates of mental disorder that were about 30% higher. There were no consistent associations between other pregnancy outcomes and mental health. Estimates of attributable risk indicated that exposure to abortion accounted for 1.5% to 5.5% of the overall rate of mental disorders. The evidence is consistent with the view that abortion may be associated with a small increase in risk of mental disorders. Other pregnancy outcomes were not related to increased risk of mental health problems.

Effect of threshold disorder on the quorum percolation model

NASA Astrophysics Data System (ADS)

Monceau, Pascal; Renault, Renaud; Métens, Stéphane; Bottani, Samuel

2016-07-01

We study the modifications induced in the behavior of the quorum percolation model on neural networks with Gaussian in-degree by taking into account an uncorrelated Gaussian thresholds variability. We derive a mean-field approach and show its relevance by carrying out explicit Monte Carlo simulations. It turns out that such a disorder shifts the position of the percolation transition, impacts the size of the giant cluster, and can even destroy the transition. Moreover, we highlight the occurrence of disorder independent fixed points above the quorum critical value. The mean-field approach enables us to interpret these effects in terms of activation probability. A finite-size analysis enables us to show that the order parameter is weakly self-averaging with an exponent independent on the thresholds disorder. Last, we show that the effects of the thresholds and connectivity disorders cannot be easily discriminated from the measured averaged physical quantities.

Disorder-induced localization in crystalline phase-change materials.

PubMed

Siegrist, T; Jost, P; Volker, H; Woda, M; Merkelbach, P; Schlockermann, C; Wuttig, M

2011-03-01

Localization of charge carriers in crystalline solids has been the subject of numerous investigations over more than half a century. Materials that show a metal-insulator transition without a structural change are therefore of interest. Mechanisms leading to metal-insulator transition include electron correlation (Mott transition) or disorder (Anderson localization), but a clear distinction is difficult. Here we report on a metal-insulator transition on increasing annealing temperature for a group of crystalline phase-change materials, where the metal-insulator transition is due to strong disorder usually associated only with amorphous solids. With pronounced disorder but weak electron correlation, these phase-change materials form an unparalleled quantum state of matter. Their universal electronic behaviour seems to be at the origin of the remarkable reproducibility of the resistance switching that is crucial to their applications in non-volatile-memory devices. Controlling the degree of disorder in crystalline phase-change materials might enable multilevel resistance states in upcoming storage devices.

Ultrasound Imaging of Muscle Contraction of the Tibialis Anterior in Patients with Facioscapulohumeral Dystrophy.

PubMed

Gijsbertse, Kaj; Goselink, Rianne; Lassche, Saskia; Nillesen, Maartje; Sprengers, André; Verdonschot, Nico; van Alfen, Nens; de Korte, Chris

2017-11-01

A need exists for biomarkers to diagnose, quantify and longitudinally follow facioscapulohumeral muscular dystrophy (FSHD) and many other neuromuscular disorders. Furthermore, the pathophysiological mechanisms leading to muscle weakness in most neuromuscular disorders are not completely understood. Dynamic ultrasound imaging (B-mode image sequences) in combination with speckle tracking is an easy, applicable and patient-friendly imaging tool to visualize and quantify muscle deformation. This dynamic information provides insight in the pathophysiological mechanisms and may help to distinguish the various stages of diseased muscle in FSHD. In this proof-of-principle study, we applied a speckle tracking technique to 2-D ultrasound image sequences to quantify the deformation of the tibialis anterior muscle in patients with FSHD and in healthy controls. The resulting deformation patterns were compared with muscle ultrasound echo intensity analysis (a measure of fat infiltration and dystrophy) and clinical outcome measures. Of the four FSHD patients, two patients had severe peroneal weakness and two patients had mild peroneal weakness on clinical examination. We found a markedly varied muscle deformation pattern between these groups: patients with severe peroneal weakness showed a different motion pattern of the tibialis anterior, with overall less displacement of the central tendon region, while healthy patients showed a non-uniform displacement pattern, with the central aponeurosis showing the largest displacement. Hence, dynamic muscle ultrasound of the tibialis anterior muscle in patients with FSHD revealed a distinctively different tissue deformation pattern among persons with and without tibialis anterior weakness. These findings could clarify the understanding of the pathophysiology of muscle weakness in FSHD patients. In addition, the change in muscle deformation shows good correlation with clinical measures and quantitative muscle ultrasound measurements. In conclusion, dynamic ultrasound in combination with speckle tracking allows the study of the effects of muscle pathology in relation to strength, force transmission and movement generation. Although further research is required, this technique can develop into a biomarker to quantify muscle disease severity. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Potential Benefits of Manmade Opals Demonstrated for First Time (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

NREL experiments show that disordered inverse opals significantly scatter and trap near-infrared light, with possible impact on optoelectronic materials. Inverse opals, familiar in the form of brilliantly colored opal gemstones, are a class of materials that has astounding optical properties. Scientists have been exploring the ability of inverse opals to manipulate light in the hopes of harnessing this capacity for advanced technologies such as displays, detectors, lasers, and photovoltaics. A research group at the National Renewable Energy Laboratory (NREL) discovered that man-made inverse opal films containing significant morphological disorder exhibit substantial light scattering, consequently trapping wavelengths in the near-infrared (NIR),more » which is important to a number of technologies. This discovery is the first experimental evidence to validate a 2005 theoretical model predicting the confinement of light in such structures, and it holds great promise for improving the performance of technologies that rely on careful light control. This breakthrough also makes possible optoelectronic technologies that use a range of low-cost molecular and semiconductor species that otherwise absorb light too weakly to be useful. The disordered inverse opal architecture validates the theoretical model that predicts the diffusion and confinement of light in such structures. Electrochemically deposited CdSe inverse opal films containing significant morphological disorder exhibit substantial light scattering and consequent NIR light trapping. This discovery holds promise for NIR light management in optoelectronic technologies, particularly those involving weakly absorbing molecular and semiconductor photomaterials.« less

Channeling of Branched Flow in Weakly Scattering Anisotropic Media.

PubMed

Degueldre, Henri; Metzger, Jakob J; Schultheis, Erik; Fleischmann, Ragnar

2017-01-13

When waves propagate through weakly scattering but correlated, disordered environments they are randomly focused into pronounced branchlike structures, a phenomenon referred to as branched flow, which has been studied in a wide range of isotropic random media. In many natural environments, however, the fluctuations of the random medium typically show pronounced anisotropies. A prominent example is the focusing of tsunami waves by the anisotropic structure of the ocean floor topography. We study the influence of anisotropy on such natural focusing events and find a strong and nonintuitive dependence on the propagation angle which we explain by semiclassical theory.

Preschool Anxiety Disorders in Pediatric Primary Care: Prevalence and Comorbidity

PubMed Central

Franz, Lauren; Angold, Adrian; Copeland, William; Costello, E. Jane; Towe-Goodman, Nissa; Egger, Helen

2013-01-01

Objective We sought to establish prevalence rates and detail patterns of comorbidity for generalized anxiety disorder, separation anxiety disorder, and social phobia, in preschool aged children. Method The Duke Preschool Anxiety Study, a screen-stratified, cross-sectional study, drew from pediatric primary-care and oversampled for children at risk for anxiety. 917 parents of preschoolers (aged 2 to 5 years) completed the Preschool Age Psychiatric Assessment. Results Generalized anxiety disorder, separation anxiety disorder, and social phobia are common in preschool-aged children attending pediatric primary care. Three quarters of preschoolers with an anxiety disorder only had a single anxiety disorder. Generalized anxiety disorder displayed the greatest degree of comorbidity: with separation anxiety disorder (odds ratio [OR] = 4.1, 95% CI, 2.0–8.5), social phobia (OR = 6.4, 95% CI, 3.1–13.4), disruptive behavior disorders (OR = 5.1, 95% CI, 1.6–15.8), and depression (OR = 3.7, 95% CI, 1.1–12.4). Conclusions The weakness of association between generalized anxiety disorder and depression stands in contrast to substantial associations between these 2 disorders reported in older individuals. Attenuated associations in preschool aged children could translate into clinical opportunities for targeted early interventions, aimed at modifying the developmental trajectory of anxiety disorders. PMID:24290462

X-ray crystal structure of plasmin with tranexamic acid-derived active site inhibitors.

PubMed

Law, Ruby H P; Wu, Guojie; Leung, Eleanor W W; Hidaka, Koushi; Quek, Adam J; Caradoc-Davies, Tom T; Jeevarajah, Devadharshini; Conroy, Paul J; Kirby, Nigel M; Norton, Raymond S; Tsuda, Yuko; Whisstock, James C

2017-05-09

The zymogen protease plasminogen and its active form plasmin perform key roles in blood clot dissolution, tissue remodeling, cell migration, and bacterial pathogenesis. Dysregulation of the plasminogen/plasmin system results in life-threatening hemorrhagic disorders or thrombotic vascular occlusion. Accordingly, inhibitors of this system are clinically important. Currently, tranexamic acid (TXA), a molecule that prevents plasminogen activation through blocking recruitment to target substrates, is the most widely used inhibitor for the plasminogen/plasmin system in therapeutics. However, TXA lacks efficacy on the active form of plasmin. Thus, there is a need to develop specific inhibitors that target the protease active site. Here we report the crystal structures of plasmin in complex with the novel YO ( trans -4-aminomethylcyclohexanecarbonyl-l-tyrosine- n -octylamide) class of small molecule inhibitors. We found that these inhibitors form key interactions with the S1 and S3' subsites of the catalytic cleft. Here, the TXA moiety of the YO compounds inserts into the primary (S1) specificity pocket, suggesting that TXA itself may function as a weak plasmin inhibitor, a hypothesis supported by subsequent biochemical and biophysical analyses. Mutational studies reveal that F587 of the S' subsite plays a key role in mediating the inhibitor interaction. Taken together, these data provide a foundation for the future development of small molecule inhibitors to specifically regulate plasmin function in a range of diseases and disorders.

X-ray crystal structure of plasmin with tranexamic acid–derived active site inhibitors

PubMed Central

Wu, Guojie; Leung, Eleanor W. W.; Hidaka, Koushi; Quek, Adam J.; Caradoc-Davies, Tom T.; Jeevarajah, Devadharshini; Kirby, Nigel M.; Norton, Raymond S.; Tsuda, Yuko; Whisstock, James C.

2017-01-01

The zymogen protease plasminogen and its active form plasmin perform key roles in blood clot dissolution, tissue remodeling, cell migration, and bacterial pathogenesis. Dysregulation of the plasminogen/plasmin system results in life-threatening hemorrhagic disorders or thrombotic vascular occlusion. Accordingly, inhibitors of this system are clinically important. Currently, tranexamic acid (TXA), a molecule that prevents plasminogen activation through blocking recruitment to target substrates, is the most widely used inhibitor for the plasminogen/plasmin system in therapeutics. However, TXA lacks efficacy on the active form of plasmin. Thus, there is a need to develop specific inhibitors that target the protease active site. Here we report the crystal structures of plasmin in complex with the novel YO (trans-4-aminomethylcyclohexanecarbonyl-l-tyrosine-n-octylamide) class of small molecule inhibitors. We found that these inhibitors form key interactions with the S1 and S3′ subsites of the catalytic cleft. Here, the TXA moiety of the YO compounds inserts into the primary (S1) specificity pocket, suggesting that TXA itself may function as a weak plasmin inhibitor, a hypothesis supported by subsequent biochemical and biophysical analyses. Mutational studies reveal that F587 of the S′ subsite plays a key role in mediating the inhibitor interaction. Taken together, these data provide a foundation for the future development of small molecule inhibitors to specifically regulate plasmin function in a range of diseases and disorders. PMID:29296720

Impulse Propagation in Disordered Hertzian Chains

NASA Astrophysics Data System (ADS)

Manciu, Marian; Sen, Surajit; Hurd, Alan J.

2000-03-01

It was shown by Nesterenko [1] that an impulse initiated at an end of a chain of elastic grains in mutual contact, i.e., interacting via the nonlinear Hertz potential, travels as a soliton-like object. Recent theoretical [2], experimental [3] and numerical studies [4] have validated his findings. In the presentation we shall examine the propagation of an impulse in an imperfect system that is characterized by grains composed of different elastic materials, different sizes, shapes and velocity-dependent friction. Our study shows that even in the presence of considerable disorder, most of the energy still travels as a weakly dispersive bundle of energy. According to our calculations, the amplitude, position and geometry of the leading pulse are related to chain disorder via simple scaling laws. We shall comment upon the inverse problem of determining the material properties by studying the pulse propagation, with many potential applications. [1] V.F. Nesterenko, J Appl Mech Tech Phys 5, 733 (1983) [2] S. Sen and M. Manciu, Physica A 268, 644 (1999); A. Chatterjee, Phys Rev E 59, 5912 (1999) [3] C. Coste, E. Falcon and S. Fauve, Phys Rev E 56, 6104 (1997); E.J. Hinch and S. Saint-Jean, Proc R Soc A 455, 3201 (1999) [4] M. Manciu, V. Tehan and S. Sen, Chaos (in press)

Disorders of the lower cranial nerves

PubMed Central

Finsterer, Josef; Grisold, Wolfgang

2015-01-01

Lesions of the lower cranial nerves (LCN) are due to numerous causes, which need to be differentiated to optimize management and outcome. This review aims at summarizing and discussing diseases affecting LCN. Review of publications dealing with disorders of the LCN in humans. Affection of multiple LCN is much more frequent than the affection of a single LCN. LCN may be affected solely or together with more proximal cranial nerves, with central nervous system disease, or with nonneurological disorders. LCN lesions have to be suspected if there are typical symptoms or signs attributable to a LCN. Causes of LCN lesions can be classified as genetic, vascular, traumatic, iatrogenic, infectious, immunologic, metabolic, nutritional, degenerative, or neoplastic. Treatment of LCN lesions depends on the underlying cause. An effective treatment is available in the majority of the cases, but a prerequisite for complete recovery is the prompt and correct diagnosis. LCN lesions need to be considered in case of disturbed speech, swallowing, coughing, deglutition, sensory functions, taste, or autonomic functions, neuralgic pain, dysphagia, head, pharyngeal, or neck pain, cardiac or gastrointestinal compromise, or weakness of the trapezius, sternocleidomastoid, or the tongue muscles. To correctly assess manifestations of LCN lesions, precise knowledge of the anatomy and physiology of the area is required. PMID:26167022

Anxiety and its disorders as risk factors for suicidal thoughts and behaviors: A meta-analytic review

PubMed Central

Bentley, Kate H.; Franklin, Joseph C.; Ribeiro, Jessica D.; Kleiman, Evan M.; Fox, Kathryn R.; Nock, Matthew K.

2016-01-01

Suicidal thoughts and behaviors are highly prevalent public health problems with devastating consequences. There is an urgent need to improve our understanding of risk factors for suicide to identify effective intervention targets. The aim of this meta-analysis was to examine the magnitude and clinical utility of anxiety and its disorders as risk factors for suicide ideation, attempts, and deaths. We conducted a literature search through December 2014; of the 65 articles meeting our inclusion criteria, we extracted 180 cases in which an anxiety-specific variable was used to longitudinally predict a suicide-related outcome. Results indicated that anxiety is a statistically significant, yet weak, predictor of suicide ideation (OR=1.49, 95% CI: 1.18, 1.88) and attempts (OR=1.64, 95% CI: 1.47, 1.83), but not deaths (OR=1.01, 95% CI: 0.87, 1.18). The strongest associations were observed for PTSD. Estimates were reduced after accounting for publication bias, and diagnostic accuracy analyses indicated acceptable specificity but poor sensitivity. Overall, the extant literature suggests that anxiety and its disorders, at least when these constructs are measured in isolation and as trait-like constructs, are relatively weak predictors of suicidal thoughts and behaviors over long follow-up periods. Implications for future research priorities are discussed. PMID:26688478

Impaired recognition of facial emotions from low-spatial frequencies in Asperger syndrome.

PubMed

Kätsyri, Jari; Saalasti, Satu; Tiippana, Kaisa; von Wendt, Lennart; Sams, Mikko

2008-01-01

The theory of 'weak central coherence' [Happe, F., & Frith, U. (2006). The weak coherence account: Detail-focused cognitive style in autism spectrum disorders. Journal of Autism and Developmental Disorders, 36(1), 5-25] implies that persons with autism spectrum disorders (ASDs) have a perceptual bias for local but not for global stimulus features. The recognition of emotional facial expressions representing various different levels of detail has not been studied previously in ASDs. We analyzed the recognition of four basic emotional facial expressions (anger, disgust, fear and happiness) from low-spatial frequencies (overall global shapes without local features) in adults with an ASD. A group of 20 participants with Asperger syndrome (AS) was compared to a group of non-autistic age- and sex-matched controls. Emotion recognition was tested from static and dynamic facial expressions whose spatial frequency contents had been manipulated by low-pass filtering at two levels. The two groups recognized emotions similarly from non-filtered faces and from dynamic vs. static facial expressions. In contrast, the participants with AS were less accurate than controls in recognizing facial emotions from very low-spatial frequencies. The results suggest intact recognition of basic facial emotions and dynamic facial information, but impaired visual processing of global features in ASDs.

Random electric field instabilities of relaxor ferroelectrics

NASA Astrophysics Data System (ADS)

Arce-Gamboa, José R.; Guzmán-Verri, Gian G.

2017-06-01

Relaxor ferroelectrics are complex oxide materials which are rather unique to study the effects of compositional disorder on phase transitions. Here, we study the effects of quenched cubic random electric fields on the lattice instabilities that lead to a ferroelectric transition and show that, within a microscopic model and a statistical mechanical solution, even weak compositional disorder can prohibit the development of long-range order and that a random field state with anisotropic and power-law correlations of polarization emerges from the combined effect of their characteristic dipole forces and their inherent charge disorder. We compare and reproduce several key experimental observations in the well-studied relaxor PbMg1/3Nb2/3O3-PbTiO3.

Depinning of the Bragg glass in a point disordered model superconductor.

PubMed

Olsson, Peter

2007-03-02

We perform simulations of the three-dimensional frustrated anisotropic XY model with point disorder as a model of a type-II superconductor with quenched point pinning in a magnetic field and a weak applied current. Using resistively shunted junction dynamics, we find a critical current I_{c} that separates a creep region with immeasurably low voltage from a region with a voltage V proportional, variant(I-I_{c}) and also identify the mechanism behind this behavior. It also turns out that data at fixed disorder strength may be collapsed by plotting V versus TI, where T is the temperature, though the reason for this behavior as yet not is fully understood.

Random hopping fermions on bipartite lattices: density of states, inverse participation ratios, and their correlations in a strong disorder regime

NASA Astrophysics Data System (ADS)

Yamada, Hiroki; Fukui, Takahiro

2004-02-01

We study Anderson localization of non-interacting random hopping fermions on bipartite lattices in two dimensions, focusing our attention to strong disorder features of the model. We concentrate ourselves on specific models with a linear dispersion in the vicinity of the band center, which can be described by a Dirac fermion in the continuum limit. Based on the recent renormalization group method developed by Carpentier and Le Doussal for the XY gauge glass model, we calculate the density of states, inverse participation ratios, and their spatial correlations. It turns out that their behavior is quite different from those expected within naive weak disorder approaches.

Decoherence of high-energy electrons in weakly disordered quantum Hall edge states

NASA Astrophysics Data System (ADS)

Nigg, Simon E.; Lunde, Anders Mathias

2016-07-01

We investigate theoretically the phase coherence of electron transport in edge states of the integer quantum Hall effect at filling factor ν =2 , in the presence of disorder and inter edge state Coulomb interaction. Within a Fokker-Planck approach, we calculate analytically the visibility of the Aharonov-Bohm oscillations of the current through an electronic Mach-Zehnder interferometer. In agreement with recent experiments, we find that the visibility is independent of the energy of the current-carrying electrons injected high above the Fermi sea. Instead, it is the amount of disorder at the edge that sets the phase space available for inter edge state energy exchange and thereby controls the visibility suppression.

Mental health problems and post-migration stress among multi-traumatized refugees attending outpatient clinics upon resettlement to Norway.

PubMed

Teodorescu, Dinu-Stefan; Heir, Trond; Hauff, Edvard; Wentzel-Larsen, Tore; Lien, Lars

2012-08-01

Refugees have often been exposed to multiple traumas making them prone to mental health problems later. The aim of this study is to describe the prevalence and symptom load of psychiatric disorders in refugees admitted to psychiatric outpatient clinics and to investigate the relationship between multiple exposure to traumatic events, the severity of traumatic symptoms and post-migration stressors. A clinical sample of 61 refugee outpatients from psychiatric clinics in Southern Norway was cross-sectionally examined using three structured clinical interviews (SCID-PTSD, SIDES and MINI) and self-report psychometric instruments (HSCL-25, IES-R). Post-traumatic Stress Disorder (PTSD) was diagnosed in 82% of the patients, while Disorders of Extreme Stress Not Otherwise Specified (DESNOS) was present in 16% of them. Comorbidity was considerable; 64% of the patients had both PTSD and major depression disorder (MDD) and 80% of those who had PTSD had three or more additional diagnoses. Multi-traumatized refugees in outpatient clinics have high prevalence of PTSD, DESNOS, comorbid depression and anxiety disorders. A more severe symptomatology was found in patients diagnosed with both PTSD and DESNOS, than in those diagnosed with only PTSD. Higher rates of unemployment, weak social network and weak social integration were also prevalent in these outpatients, and related to increased psychiatric comorbidity and severity of symptoms. Further research may clarify the existence of a cumulative relationship between pre-resettlement traumas and post-resettlement stressors in the mental health of refugees, which in turn may help to improve therapeutic interventions. © 2012 The Authors. Scandinavian Journal of Psychology © 2012 The Scandinavian Psychological Associations.

Interventions for disorder and severe intoxication in and around licensed premises, 1989-2009.

PubMed

Brennan, Iain; Moore, Simon C; Byrne, Ellie; Murphy, Simon

2011-04-01

To systematically review rigorous evaluation studies into the effectiveness of interventions in and around licensed premises that aimed to reduce severe intoxication and disorder. A systematic search was conducted. Papers that rigorously evaluated interventions based in and around licensed premises to reduce disorder or intoxication were included. Fifteen studies were identified, three randomized controlled trials and 12 non-randomized quasi-experimental evaluations. Outcome measures were intoxication (n = 6), disorder (n = 6) and intoxication and disorder (n = 3). Interventions included responsible beverage service training (n = 5), server violence prevention training (n = 1), enhanced enforcement of licensing regulations (n = 1), multi-level interventions (n = 5), licensee accords (n = 2) and a risk-focused consultation (n = 1). Intervention effects varied, even across studies using similar interventions. Server training courses that are designed to reduce disorder have some potential, although there is a lack of evidence to support their use to reduce intoxication and the evidence base is weak. © 2011 The Authors, Addiction © 2011 Society for the Study of Addiction.

Good Use of a `Bad' Metaphor. Entropy as Disorder

NASA Astrophysics Data System (ADS)

Haglund, Jesper

2017-05-01

Entropy is often introduced to students through the use of the disorder metaphor. However, many weaknesses and limitations of this metaphor have been identified, and it has therefore been argued that it is more harmful than useful in teaching. For instance, under the influence of the disorder metaphor, students tend to focus on spatial configuration with regard to entropy but disregard the role of energy, which may lead their intuition astray in problem solving. Albeit so, a review of research of students' ideas about entropy in relation to the disorder metaphor shows that students can use the metaphor in developing a more nuanced, complex view of the concept, by connecting entropy as disorder to other concepts such as microstates and spreading. The disorder metaphor—in combination with other explanatory approaches—can be used as a resource for learning, in giving students an early flavour of what entropy means, so long as we acknowledge its limitations; we can put this "bad" metaphor to good use in teaching.

Specific Learning Difficulties--What Teachers Need to Know

ERIC Educational Resources Information Center

Hudson, Diana

2015-01-01

This book clearly explains what Specific Learning Difficulties (SpLD) are, and describes the symptoms of conditions most commonly encountered in the mainstream classroom: dyslexia, dyspraxia, dyscalculia, dysgraphia, Autism Spectrum Disorder, ADHD, and OCD. The author provides an overview of the strengths and weaknesses commonly associated with…

Cognitive Profile of Turner Syndrome

ERIC Educational Resources Information Center

Hong, David; Kent, Jamie Scaletta; Kesler, Shelli

2009-01-01

Turner syndrome (TS) is a relatively common neurogenetic disorder characterized by complete or partial monosomy-X in a phenotypic female. TS is associated with a cognitive profile that typically includes intact intellectual function and verbal abilities with relative weaknesses in visual-spatial, executive, and social cognitive domains. In this…

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP): An Uncommon Manifestation of Systemic Lupus Erythematosus (SLE)

PubMed Central

Abraham, Hrudya; Kuzhively, Jose; Rizvi, Syed W.

2017-01-01

Patient: Female, 40 Final Diagnosis: Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) Symptoms: Gait disorder Medication: — Clinical Procedure: — Specialty: Rheumatology Objective: Rare disease Background: Chronic inflammatory demyelinating polyneuropathy (CIDP) is an uncommon manifestation of systemic lupus erythematosus (SLE). We report a case of SLE presenting as CIDP and discuss the diagnosis, management, and prognosis of CIDP. Case Report: A 40-year-old woman with a past medical history of SLE treated with hydroxychloroquine presented with bilateral, progressive, ascending, sensory and motor neuropathy. Physical examination showed weakness and reduced temperature of all extremities, reduced pinprick and vibration sense of the distal extremities, loss of reflexes, and walking with a wide-based unsteady gait. Laboratory investigations showed positive antinuclear antibodies (ANA), anti-(smooth muscle (SM) antibody, anti-RNP antibody, anti-SSA antibody, anti-ds-DNA antibody, and an erythrocyte sedimentation rate (ESR) of 75 mm/hr, low C4, leukopenia, and anemia. Electromyography (EMG) confirmed the diagnosis of CIDP. The patient’s neuropathy and muscle weakness improved on treatment with intravenous immunoglobulin (IVIG) and high-dose steroids. Conclusions: The early clinical diagnosis of CIDP, supported by serological autoantibody profiles associated with SLE, can predict a good response to steroids. Most patients with CIDP are treated successfully with steroids if the diagnosis is made early. IVIG, plasmapheresis, or immunosuppressive therapy should be considered if there is no response to steroids. PMID:28894082

Percolation thresholds and fractal dimensions for square and cubic lattices with long-range correlated defects

NASA Astrophysics Data System (ADS)

Zierenberg, Johannes; Fricke, Niklas; Marenz, Martin; Spitzner, F. P.; Blavatska, Viktoria; Janke, Wolfhard

2017-12-01

We study long-range power-law correlated disorder on square and cubic lattices. In particular, we present high-precision results for the percolation thresholds and the fractal dimension of the largest clusters as a function of the correlation strength. The correlations are generated using a discrete version of the Fourier filtering method. We consider two different metrics to set the length scales over which the correlations decay, showing that the percolation thresholds are highly sensitive to such system details. By contrast, we verify that the fractal dimension df is a universal quantity and unaffected by the choice of metric. We also show that for weak correlations, its value coincides with that for the uncorrelated system. In two dimensions we observe a clear increase of the fractal dimension with increasing correlation strength, approaching df→2 . The onset of this change does not seem to be determined by the extended Harris criterion.

Dephasing Catastrophe in 4-ε Dimensions: A Possible Instability of the Ergodic (Many-Body-Delocalized) Phase.

PubMed

Liao, Yunxiang; Foster, Matthew S

2018-06-08

In two dimensions, dephasing by a bath cuts off Anderson localization that would otherwise occur at any energy density for fermions with disorder. For an isolated system with short-range interactions, the system can be its own bath, exhibiting diffusive (non-Markovian) thermal density fluctuations. We recast the dephasing of weak localization due to a diffusive bath as a self-interacting polymer loop. We investigate the critical behavior of the loop in d=4-ε dimensions, and find a nontrivial fixed point corresponding to a temperature T^{*}∼ε>0 where the dephasing time diverges. Assuming that this fixed point survives to ε=2, we associate it with a possible instability of the ergodic phase. Our approach may open a new line of attack against the problem of the ergodic to many-body-localized phase transition in d>1 spatial dimensions.

Dephasing Catastrophe in 4 -ɛ Dimensions: A Possible Instability of the Ergodic (Many-Body-Delocalized) Phase

NASA Astrophysics Data System (ADS)

Liao, Yunxiang; Foster, Matthew S.

2018-06-01

In two dimensions, dephasing by a bath cuts off Anderson localization that would otherwise occur at any energy density for fermions with disorder. For an isolated system with short-range interactions, the system can be its own bath, exhibiting diffusive (non-Markovian) thermal density fluctuations. We recast the dephasing of weak localization due to a diffusive bath as a self-interacting polymer loop. We investigate the critical behavior of the loop in d =4 -ɛ dimensions, and find a nontrivial fixed point corresponding to a temperature T*˜ɛ >0 where the dephasing time diverges. Assuming that this fixed point survives to ɛ =2 , we associate it with a possible instability of the ergodic phase. Our approach may open a new line of attack against the problem of the ergodic to many-body-localized phase transition in d >1 spatial dimensions.

Clinical Manifestations and Overall Management Strategies for Duchenne Muscular Dystrophy.

PubMed

Tsuda, Takeshi

2018-01-01

Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder that causes progressive weakness and wasting of skeletal muscular and myocardium in boys due to mutation of dystrophin. The structural integrity of each individual skeletal and cardiac myocyte is significantly compromised upon physical stress due to the absence of dystrophin. The progressive destruction of systemic musculature and myocardium causes affected patients to develop multiple organ disabilities, including loss of ambulation, physical immobility, neuromuscular scoliosis, joint contracture, restrictive lung disease, obstructive sleep apnea, and cardiomyopathy. There are some central nervous system-related medical problems, as dystrophin is also expressed in the neuronal tissues. Although principal management is to mainly delay the pathological process, an enhanced understanding of underlying pathological processes has significantly improved quality of life and longevity for DMD patients. Future research in novel molecular approach is warranted to answer unanswered questions.

Myasthenia Gravis: Unusual Presentations and Diagnostic Pitfalls.

PubMed

Rodolico, Carmelo; Parisi, Daniela; Portaro, Simona; Biasini, Fiammetta; Sinicropi, Stefano; Ciranni, Annamaria; Toscano, Antonio; Messina, Sonia; Musumeci, Olimpia; Vita, Giuseppe; Girlanda, Paolo

2016-08-30

Myasthenia gravis (MG) is an autoimmune disorder presenting with fluctuating, fatigable muscle weakness. Initial symptoms classically involve ocular and proximal limb muscles. Rarely, MG may onset with unusual features, so it can be misdiagnosed with other neuromuscular diseases. To describe unusual and atypical presentations of MG in a large cohort of patients, considering and discussing diagnostic difficulties and pitfalls. We report on 21 out of 508 MG patients, coming to our department in the last 27 years and presenting with atypical or unusual features. The diagnosis was achieved performing a careful clinical examination, a proper neurophysiological assessment, the neostigmine test, the AChR and MuSK antibodies assay and chest CT-scan. Patients with atypical/unusual MG onset were the 4.4% of all MG patients population. We describe seven different clinical categories: asymmetric distal upper limbs weakness, foot drop, isolated triceps brachii weakness and foot drop, post exertional axial weakness with dropped head, acute facial dyplegia, limb-girdle MG and MG with sudden lower limbs weakness and recurrent falls. Atypical and unusual presentations may increase the risk to misdiagnose or delay MG diagnosis. Isolated limb-girdle presentation is the most frequent atypical form in our series.

Characteristics of weak base-induced vacuoles formed around individual acidic organelles.

PubMed

Hiruma, Hiromi; Kawakami, Tadashi

2011-01-01

We have previously found that the weak base 4-aminopyridine induces Brownian motion of acidic organelles around which vacuoles are formed, causing organelle traffic disorder in neurons. Our present study investigated the characteristics of vacuoles induced by weak bases (NH(4)Cl, aminopyridines, and chloroquine) using mouse cells. Individual vacuoles included acidic organelles identified by fluorescent protein expression. Mitochondria and actin filaments were extruded outside the vacuoles, composing the vacuole rim. Staining with amine-reactive fluorescence showed no protein/amino acid content in vacuoles. Thus, serous vacuolar contents are probably partitioned by viscous cytosol, other organelles, and cytoskeletons, but not membrane. The weak base (chloroquine) was immunochemically detected in intravacuolar organelles, but not in vacuoles. Early vacuolization was reversible, but long-term vacuolization caused cell death. The vacuolization and cell death were blocked by the vacuolar H(+)-ATPase inhibitor and Cl--free medium. Staining with LysoTracker or LysoSensor indicated that intravacuolar organelles were strongly acidic and vacuoles were slightly acidic. This suggests that vacuolization is caused by accumulation of weak base and H(+) in acidic organelles, driven by vacuolar H(+)-ATPase associated with Cl(-) entering, and probably by subsequent extrusion of H(+) and water from organelles to the surrounding cytoplasm.

Disorder-induced half-integer quantized conductance plateau in quantum anomalous Hall insulator-superconductor structures

NASA Astrophysics Data System (ADS)

Huang, Yingyi; Setiawan, F.; Sau, Jay D.

2018-03-01

A weak superconducting proximity effect in the vicinity of the topological transition of a quantum anomalous Hall system has been proposed as a venue to realize a topological superconductor (TSC) with chiral Majorana edge modes (CMEMs). A recent experiment [Science 357, 294 (2017), 10.1126/science.aag2792] claimed to have observed such CMEMs in the form of a half-integer quantized conductance plateau in the two-terminal transport measurement of a quantum anomalous Hall-superconductor junction. Although the presence of a superconducting proximity effect generically splits the quantum Hall transition into two phase transitions with a gapped TSC in between, in this Rapid Communication we propose that a nearly flat conductance plateau, similar to that expected from CMEMs, can also arise from the percolation of quantum Hall edges well before the onset of the TSC or at temperatures much above the TSC gap. Our Rapid Communication, therefore, suggests that, in order to confirm the TSC, it is necessary to supplement the observation of the half-quantized conductance plateau with a hard superconducting gap (which is unlikely for a disordered system) from the conductance measurements or the heat transport measurement of the transport gap. Alternatively, the half-quantized thermal conductance would also serve as a smoking-gun signature of the TSC.

A randomized, double-blind, placebo-controlled pilot study of naltrexone to counteract antipsychotic-associated weight gain: proof of concept.

PubMed

Tek, Cenk; Ratliff, Joseph; Reutenauer, Erin; Ganguli, Rohan; O'Malley, Stephanie S

2014-10-01

Patients with schizophrenia experience higher rates of obesity as well as related morbidity and mortality than the general population does. Women with schizophrenia are at particular risk for antipsychotic-associated weight gain, obesity, and related medical disorders such as diabetes and cardiovascular disease. Given preclinical studies revealing the role of the endogenous opioid systems in human appetite and the potential of antipsychotic medications to interfere with this system, we hypothesized that opioid antagonists may be beneficial in arresting antipsychotic-associated weight gain and promoting further weight loss in women with schizophrenia. In the present study, 24 overweight women with a diagnosis of schizophrenia or schizoaffective disorder were randomized to placebo or naltrexone (NTX) 25 mg/d for 8 weeks. The primary outcome measure was a change in body weight from baseline. The patients in the NTX group had significant weight loss (-3.40 kg) compared with weight gain (+1.37 kg) in the patients in the placebo group. Mainly, nondiabetic subjects lost weight in the NTX arm. These data support the need to further investigate the role of D2 blockade in reducing food reward-based overeating. A larger study addressing the weaknesses of this pilot study is currently underway.

Analysis of Brain Recurrence

NASA Astrophysics Data System (ADS)

Frilot, Clifton; Kim, Paul Y.; Carrubba, Simona; McCarty, David E.; Chesson, Andrew L.; Marino, Andrew A.

Analysis of Brain Recurrence (ABR) is a method for extracting physiologically significant information from the electroencephalogram (EEG), a non-stationary electrical output of the brain, the ultimate complex dynamical system. ABR permits quantification of temporal patterns in the EEG produced by the non-autonomous differential laws that govern brain metabolism. In the context of appropriate experimental and statistical designs, ABR is ideally suited to the task of interpreting the EEG. Present applications of ABR include discovery of a human magnetic sense, increased mechanistic understanding of neuronal membrane processes, diagnosis of degenerative neurological disease, detection of changes in brain metabolism caused by weak environmental electromagnetic fields, objective characterization of the quality of human sleep, and evaluation of sleep disorders. ABR has important beneficial implications for the development of clinical and experimental neuroscience.

A rare association of celiac disease and aplastic anemia: case report of a child and review of literature.

PubMed

Badyal, Rama Kumari; Sachdeva, Man Updesh Singh; Varma, Neelam; Thapa, Babu Ram

2014-01-01

An association between severe aplastic anemia and other autoimmune diseases is rare and has been described in adults for eosinophilic fasciitis, thymomas, systemic lupus erythematosus, and thyroid disorders. Herein we report a patient with celiac disease who was not strictly following a gluten-free diet and presented with progressive pallor, fever, and weakness of 1 month's duration. On investigation, he had pancytopenia, which on subsequent evaluation revealed aplastic anemia. An association between aplastic anemia and celiac disease has rarely been reported. To the best of author's knowledge, only 1 pediatric case of celiac disease associated with aplastic anemia has been published. This is the second report to suggest such an association in children.

Viscous magnetoresistance of correlated electron liquids

NASA Astrophysics Data System (ADS)

Levchenko, Alex; Xie, Hong-Yi; Andreev, A. V.

2017-03-01

We develop a theory of magnetoresistance of two-dimensional electron systems in a smooth disorder potential in the hydrodynamic regime. Our theory applies to two-dimensional semiconductor structures with strongly correlated carriers when the mean free path due to electron-electron collisions is sufficiently short. The dominant contribution to magnetoresistance arises from the modification of the flow pattern by the Lorentz force, rather than the magnetic field dependence of the kinetic coefficients of the electron liquid. The resulting magnetoresistance is positive and quadratic at weak fields. Although the resistivity is governed by both the viscosity and thermal conductivity of the electron fluid, the magnetoresistance is controlled by the viscosity only. This enables the extraction of viscosity of the electron liquid from magnetotransport measurements.

Brain Structural Effects of Psychopharmacological Treatment in Bipolar Disorder

PubMed Central

McDonald, Colm

2015-01-01

Bipolar disorder is associated with subtle neuroanatomical deficits including lateral ventricular enlargement, grey matter deficits incorporating limbic system structures, and distributed white matter pathophysiology. Substantial heterogeneity has been identified by structural neuroimaging studies to date and differential psychotropic medication use is potentially a substantial contributor to this. This selective review of structural neuroimaging and diffusion tensor imaging studies considers evidence that lithium, mood stabilisers, antipsychotic medication and antidepressant medications are associated with neuroanatomical variation. Most studies are negative and suffer from methodological weaknesses in terms of directly assessing medication effects on neuroanatomy, since they commonly comprise posthoc assessments of medication associations with neuroimaging metrics in small heterogenous patient groups. However the studies which report positive findings tend to form a relatively consistent picture whereby lithium and antiepileptic mood stabiliser use is associated with increased regional grey matter volume, especially in limbic structures. These findings are further supported by the more methodologically robust studies which include large numbers of patients or repeated intra-individual scanning in longitudinal designs. Some similar findings of an apparently ameliorative effect of lithium on white matter microstructure are also emerging. There is less support for an effect of antipsychotic or antidepressant medication on brain structure in bipolar disorder, but these studies are further limited by methodological difficulties. In general the literature to date supports a normalising effect of lithium and mood stabilisers on brain structure in bipolar disorder, which is consistent with the neuroprotective characteristics of these medications identified by preclinical studies. PMID:26412064

Brain Structural Effects of Psychopharmacological Treatment in Bipolar Disorder.

PubMed

McDonald, Colm

2015-01-01

Bipolar disorder is associated with subtle neuroanatomical deficits including lateral ventricular enlargement, grey matter deficits incorporating limbic system structures, and distributed white matter pathophysiology. Substantial heterogeneity has been identified by structural neuroimaging studies to date and differential psychotropic medication use is potentially a substantial contributor to this. This selective review of structural neuroimaging and diffusion tensor imaging studies considers evidence that lithium, mood stabilisers, antipsychotic medication and antidepressant medications are associated with neuroanatomical variation. Most studies are negative and suffer from methodological weaknesses in terms of directly assessing medication effects on neuroanatomy, since they commonly comprise posthoc assessments of medication associations with neuroimaging metrics in small heterogenous patient groups. However the studies which report positive findings tend to form a relatively consistent picture whereby lithium and antiepileptic mood stabiliser use is associated with increased regional grey matter volume, especially in limbic structures. These findings are further supported by the more methodologically robust studies which include large numbers of patients or repeated intra-individual scanning in longitudinal designs. Some similar findings of an apparently ameliorative effect of lithium on white matter microstructure are also emerging. There is less support for an effect of antipsychotic or antidepressant medication on brain structure in bipolar disorder, but these studies are further limited by methodological difficulties. In general the literature to date supports a normalising effect of lithium and mood stabilisers on brain structure in bipolar disorder, which is consistent with the neuroprotective characteristics of these medications identified by preclinical studies.

Treatment of cardiomyopathy and rhabdomyolysis in long-chain fat oxidation disorders using an anaplerotic odd-chain triglyceride

PubMed Central

Roe, Charles R.; Sweetman, Lawrence; Roe, Diane S.; David, France; Brunengraber, Henri

2002-01-01

The current dietary treatment of long-chain fatty acid oxidation defects (high carbohydrate with medium-even-chain triglycerides and reduced amounts of long-chain fats) fails, in many cases, to prevent cardiomyopathy, rhabdomyolysis, and muscle weakness. We hypothesized that the apparent defect in energy production results from a depletion of the catalytic intermediates of the citric acid cycle via leakage through cell membranes (cataplerosis). We further hypothesized that replacing dietary medium-even-chain fatty acids (precursors of acetyl-CoA) by medium-odd-chain fatty acids (precursors of acetyl-CoA and anaplerotic propionyl-CoA) would restore energy production and improve cardiac and skeletal muscle function. We fed subjects with long-chain defects a controlled diet in which the fat component was switched from medium-even-chain triglycerides to triheptanoin. In three patients with very-long-chain acyl-CoA dehydrogenase deficiency, this treatment led rapidly to clinical improvement that included the permanent disappearance of chronic cardiomyopathy, rhabdomyolysis, and muscle weakness (for more than 2 years in one child), and of rhabdomyolysis and weakness in the others. There was no evidence of propionyl overload in these patients. The treatment has been well tolerated for up to 26 months and opens new avenues for the management of patients with mitochondrial fat oxidation disorders. PMID:12122118

Weak network efficiency in young children with Autism Spectrum Disorder: Evidence from a functional near-infrared spectroscopy study.

PubMed

Li, Yanwei; Yu, Dongchuan

2016-10-01

Functional near infrared spectroscopy (fNIRS) is particularly suited for the young population and ecological measurement. However, thus far, not enough effort has been given to the clinical diagnosis of young children with Autism Spectrum Disorder (ASD) by using fNIRS. The current study provided some insights into the quantitative analysis of functional networks in young children (ages 4.8-8.0years old) with and without ASD and, in particular, investigated the network efficiency and lobe-level connectivity of their functional networks while watching a cartoon. The main results included that: (i) Weak network efficiency was observed in young children with ASD, even for a wide range of threshold for the binarization of functional networks; (ii) A maximum classification accuracy rate of 83.3% was obtained for all participants by using the k-means clustering method with network efficiencies as the feature parameters; and (iii) Weak lobe-level inter-region connections were uncovered in the right prefrontal cortex, including its linkages with the left prefrontal cortex and the bilateral temporal cortex. Such results indicate that the right prefrontal cortex might make a major contribution to the psychopathology of young children with ASD at the functional network architecture level, and at the functional lobe-connectivity level, respectively. Copyright © 2016 Elsevier Inc. All rights reserved.

Is overestimation of body size associated with neuropsychological weaknesses in anorexia nervosa?

PubMed

Øverås, Maria; Kapstad, Hilde; Brunborg, Cathrine; Landrø, Nils Inge; Rø, Øyvind

2017-03-01

Recent research indicates some evidence of neuropsychological weaknesses in visuospatial memory, central coherence and set-shifting in adults with anorexia nervosa (AN). The growing interest in neuropsychological functioning of patients with AN is based upon the assumption that neuropsychological weaknesses contribute to the clinical features of the illness. However, due to a paucity of research on the connection between neuropsychological difficulties and the clinical features of AN, this link remains hypothetical. The main objective of this study was to explore the association between specific areas of neuropsychological functioning and body size estimation in patients with AN and healthy controls. The sample consisted of 36 women diagnosed with AN and 34 healthy female controls. Participants were administered the continuous visual memory test and the recall trials of Rey Complex Figure Test to assess visual memory. Central coherence was assessed using the copy trial of Rey Complex Figure Test, and the Wisconsin Card Sorting Test was used to assess set-shifting. Body size estimation was assessed with a computerized morphing programme. The analyses showed no significant correlations between any of the neuropsychological measures and body size estimation. The results suggest that there is no association between these areas of neuropsychological difficulties and body size estimation among patients with AN. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

Rectification of Spatial Disorder

NASA Astrophysics Data System (ADS)

Um, Jaegon; Hong, Hyunsuk; Marchesoni, Fabio; Park, Hyunggyu

2012-02-01

We demonstrate that a large ensemble of noiseless globally coupled-pinned oscillators is capable of rectifying spatial disorder with spontaneous current activated through a dynamical phase transition mechanism, either of first or second order, depending on the profile of the pinning potential. In the presence of an external weak drive, the same collective mechanism can result in an absolute negative mobility, which, though not immediately related to symmetry breaking, is most prominent at the phase transition. Our results apply to a tug-of-war by competing molecular motors for bidirectional cargo transport.

Disruptive technology disorder: A past, present, and future neurologic syndrome.

PubMed

Weaver, Donald F

2017-07-25

Based upon an analysis of 6 major historical technological advances over the last 150 years, a new syndrome, disruptive technology disorder (DTD), is introduced. DTD describes the human health ailments that accompany the implementation of disruptive technologies. Elevator sickness, railway spine, and bicycle face are representative examples. Though the underlying causative disruptive technologies may differ, many neurologic symptoms (headache, dizziness, weakness) are common to multiple DTDs. Born of technology-driven societal change, DTDs manifest as a complex interplay between biological and psychological symptoms. © 2017 American Academy of Neurology.

Neurobiology of Chronic Stress-Related Psychiatric Disorders: Evidence from Molecular Imaging Studies

PubMed Central

Davis, Margaret T.; Holmes, Sophie E.; Pietrzak, Robert H.; Esterlis, Irina

2018-01-01

Chronic stress accounts for billions of dollars of economic loss annually in the United States alone, and is recognized as a major source of disability and mortality worldwide. Robust evidence suggests that chronic stress plays a significant role in the onset of severe and impairing psychiatric conditions, including major depressive disorder, bipolar disorder, and posttraumatic stress disorder. Application of molecular imaging techniques such as positron emission tomography and single photon emission computed tomography in recent years has begun to provide insight into the molecular mechanisms by which chronic stress confers risk for these disorders. The present paper provides a comprehensive review and synthesis of all positron emission tomography and single photon emission computed tomography imaging publications focused on the examination of molecular targets in individuals with major depressive disorder, posttraumatic stress disorder, or bipolar disorder to date. Critical discussion of discrepant findings and broad strengths and weaknesses of the current body of literature is provided. Recommended future directions for the field of molecular imaging to further elucidate the neurobiological substrates of chronic stress-related disorders are also discussed. This article is part of the inaugural issue for the journal focused on various aspects of chronic stress. PMID:29862379

Three-year recovery outcomes for long-term patients with co-occurring schizophrenic and substance use disorders.

PubMed

Xie, Haiyi; McHugo, Gregory J; Helmstetter, Barbara S; Drake, Robert E

2005-06-15

Little is known about the expected treatment outcomes of patients with co-occurring schizophrenic and substance use disorders. This paper reports 3-year outcomes for 152 patients with schizophrenia or schizoaffective disorder and substance use disorders, all of whom received integrated dual disorders treatments in the New Hampshire Dual Diagnosis Study. Outcomes are defined as positive coping behaviors identified by consumers as indicators of recovery. Participants improved steadily in terms of controlling symptoms of schizophrenia, actively attaining remissions from substance abuse, increasing competitive employment, increasing social contacts with non-substance abusers, and improving life satisfaction. Though successful in reducing hospitalization and homelessness, they did not increase time in independent living situations. Outcomes were only weakly interrelated, suggesting that recovery is a multidimensional concept. Neither psychotic diagnosis (schizophrenia vs. schizoaffective disorder) nor substance abuse diagnosis (alcohol vs. other drug disorder vs. both) was related to outcomes. However, these patients with co-occurring schizophrenic and substance use disorders did significantly less well than patients with co-occurring bipolar and substance use disorders in terms of hospitalization, independent living, and quality of life. Overall, the findings provide a hopeful long-term perspective for dual diagnosis patients.

Neurological manifestations of Ehlers-Danlos syndrome(s): A review

PubMed Central

Castori, Marco; C. Voermans, Nicol

2014-01-01

The term “Ehlers-Danlos syndrome” (EDS) groups together an increasing number of heritable connective tissue disorders mainly featuring joint hypermobility and related complications, dermal dysplasia with abnormal skin texture and repair, and variable range of the hollow organ and vascular dysfunctions. Although the nervous system is not considered a primary target of the underlying molecular defect, recently, increasing attention has been posed on neurological manifestations of EDSs, such as musculoskeletal pain, fatigue, headache, muscle weakness and paresthesias. Here, a comprehensive overview of neurological findings of these conditions is presented primarily intended for the clinical neurologist. Features are organized under various subheadings, including pain, fatigue, headache, stroke and cerebrovascular disease, brain and spine structural anomalies, epilepsy, muscular findings, neuropathy and developmental features. The emerging picture defines a wide spectrum of neurological manifestations that are unexpectedly common and potentially disabling. Their evaluation and correct interpretation by the clinical neurologist is crucial for avoiding superfluous investigations, wrong therapies, and inappropriate referral. A set of basic tools for patient’s recognition is offered for raising awareness among neurologists on this underdiagnosed group of hereditary disorders. PMID:25632331

Electronic disorder and magnetic-field-induced superconductivity enhancement in Fe1+y(Te1-xSex)

NASA Astrophysics Data System (ADS)

Hu, Jin; Liu, Tijiang; Qian, Bin; Mao, Zhiqiang

2012-02-01

The iron chalcogenide Fe1+y(Te1-xSex) superconductor system exhibits a unique electronic and magnetic phase diagram distinct from those seen in iron pnictides: bulk superconductivity does not appear immediately following the suppression of long-range (π,0) AFM order. Instead, an intermediate phase with weak charge carrier localization appears between AFM order and bulk superconductivity (Liu et al., Nat. Mater. 9, 719 (2010)). In this talk, we report our recent studies on the relationship between the normal state and superconducting properties in Fe1+y(Te1-xSex). We show that the superconducting volume fraction VSC and normal state metallicity significantly increase while the normal state Sommerfeld coefficient γ and Hall coefficient RH drop drastically with increasing Se content in the underdoped superconducting region. Additionally, VSC is surprisingly enhanced by magnetic field in heavily underdoped superconducting samples. The implications of these results will be discussed. Our analyses suggest that the suppression of superconductivity in the underdoped region is associated with electronic disorder caused by incoherent magnetic scattering arising from (π,0) magnetic fluctuations.

Conductivity of disordered 2d binodal Dirac electron gas: effect of internode scattering

NASA Astrophysics Data System (ADS)

Sinner, Andreas; Ziegler, Klaus

2018-07-01

We study the dc conductivity of a weakly disordered 2d Dirac electron gas with two bands and two spectral nodes, employing a field theoretical version of the Kubo-Greenwood conductivity formula. In this paper, we are concerned with the question how the internode scattering affects the conductivity. We use and compare two established techniques for treating the disorder scattering: The perturbation theory, there ladder and maximally crossed diagrams are summed up, and the functional integral approach. Both turn out to be entirely equivalent. For a large number of random potential configurations we have found only two different conductivity scenarios. Both scenarios appear independently of whether the disorder does or does not create the internode scattering. In particular, we do not confirm the conjecture that the internode scattering tends to Anderson localisation.

Spin diffusion in disordered organic semiconductors

NASA Astrophysics Data System (ADS)

Li, Ling; Gao, Nan; Lu, Nianduan; Liu, Ming; Bässler, Heinz

2015-12-01

An analytical theory for spin diffusion in disordered organic semiconductors is derived. It is based on percolation theory and variable range hopping in a disordered energy landscape with a Gaussian density of states. It describes universally the dependence of the spin diffusion on temperature, carrier density, material disorder, magnetic field, and electric field at the arbitrary magnitude of the Hubbard energy of charge pairs. It is found that, compared to the spin transport carried by carriers hopping, the spin exchange will hinder the spin diffusion process at low carrier density, even under the condition of a weak electric field. Importantly, under the influence of a bias voltage, anomalous spreading of the spin packet will lead to an abnormal temperature dependence of the spin diffusion coefficient and diffusion length. This explains the recent experimental data for spin diffusion length observed in Alq3.

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires

NASA Astrophysics Data System (ADS)

Dufouleur, J.; Veyrat, L.; Dassonneville, B.; Xypakis, E.; Bardarson, J. H.; Nowka, C.; Hampel, S.; Schumann, J.; Eichler, B.; Schmidt, O. G.; Büchner, B.; Giraud, R.

2017-04-01

Disorder remains a key limitation in the search for robust signatures of topological superconductivity in condensed matter. Whereas clean semiconducting quantum wires gave promising results discussed in terms of Majorana bound states, disorder makes the interpretation more complex. Quantum wires of 3D topological insulators offer a serious alternative due to their perfectly-transmitted mode. An important aspect to consider is the mixing of quasi-1D surface modes due to the strong degree of disorder typical for such materials. Here, we reveal that the energy broadening γ of such modes is much smaller than their energy spacing Δ, an unusual result for highly-disordered mesoscopic nanostructures. This is evidenced by non-universal conductance fluctuations in highly-doped and disordered Bi2Se3 and Bi2Te3 nanowires. Theory shows that such a unique behavior is specific to spin-helical Dirac fermions with strong quantum confinement, which retain ballistic properties over an unusually large energy scale due to their spin texture. Our result confirms their potential to investigate topological superconductivity without ambiguity despite strong disorder.

Blood lead levels in children with neurological disorders: a single centre preliminary study.

PubMed

Mahmoudian, Touran; Modaresi, Mohamadreza; Zarei, Ali; Poursafa, Parinaz; Kelishadi, Roya

2009-11-01

Lead poisoning is a potentially devastating problem among young children. Chronic low level lead exposure can lead to learning disabilities and behavior changes such as colic, insomnia, hyperactivity, impaired growth, hearing loss and upper extremity weakness. The purpose of this cross sectional study was to determine the blood lead level in children with neurological disorders in comparison with healthy controls. Blood lead concentrations were measured by flame atomic absorption spectrometry in 100 children aged 1-10 years and suffering from various neurological disorders. One hundred age and sex-matched healthy children served as controls. The mean blood lead concentration was higher in children with neurological disorders than in controls (113.2 + or - 47.5 microg/L vs 84.7 + or - 38.0 microg/L; p<0.01). Overall, 44% of children with neurological disorders and 19% of controls were found to have increased blood lead levels, i.e.>100 microg/L. An increase in blood lead level in children might be related to neurological disorders. The measurement of blood lead level might be included in diagnostic eveluation of children with neurological disorders.

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires

PubMed Central

Dufouleur, J.; Veyrat, L.; Dassonneville, B.; Xypakis, E.; Bardarson, J. H.; Nowka, C.; Hampel, S.; Schumann, J.; Eichler, B.; Schmidt, O. G.; Büchner, B.; Giraud, R.

2017-01-01

Disorder remains a key limitation in the search for robust signatures of topological superconductivity in condensed matter. Whereas clean semiconducting quantum wires gave promising results discussed in terms of Majorana bound states, disorder makes the interpretation more complex. Quantum wires of 3D topological insulators offer a serious alternative due to their perfectly-transmitted mode. An important aspect to consider is the mixing of quasi-1D surface modes due to the strong degree of disorder typical for such materials. Here, we reveal that the energy broadening γ of such modes is much smaller than their energy spacing Δ, an unusual result for highly-disordered mesoscopic nanostructures. This is evidenced by non-universal conductance fluctuations in highly-doped and disordered Bi2Se3 and Bi2Te3 nanowires. Theory shows that such a unique behavior is specific to spin-helical Dirac fermions with strong quantum confinement, which retain ballistic properties over an unusually large energy scale due to their spin texture. Our result confirms their potential to investigate topological superconductivity without ambiguity despite strong disorder. PMID:28374744

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires.

PubMed

Dufouleur, J; Veyrat, L; Dassonneville, B; Xypakis, E; Bardarson, J H; Nowka, C; Hampel, S; Schumann, J; Eichler, B; Schmidt, O G; Büchner, B; Giraud, R

2017-04-04

Disorder remains a key limitation in the search for robust signatures of topological superconductivity in condensed matter. Whereas clean semiconducting quantum wires gave promising results discussed in terms of Majorana bound states, disorder makes the interpretation more complex. Quantum wires of 3D topological insulators offer a serious alternative due to their perfectly-transmitted mode. An important aspect to consider is the mixing of quasi-1D surface modes due to the strong degree of disorder typical for such materials. Here, we reveal that the energy broadening γ of such modes is much smaller than their energy spacing Δ, an unusual result for highly-disordered mesoscopic nanostructures. This is evidenced by non-universal conductance fluctuations in highly-doped and disordered Bi2Se3 and Bi 2 Te 3 nanowires. Theory shows that such a unique behavior is specific to spin-helical Dirac fermions with strong quantum confinement, which retain ballistic properties over an unusually large energy scale due to their spin texture. Our result confirms their potential to investigate topological superconductivity without ambiguity despite strong disorder.

Reading Comprehension and Autism in the Primary General Education Classroom

ERIC Educational Resources Information Center

Nguyen, Neal Nghia; Leytham, Patrick; Schaefer Whitby, Peggy; Gelfer, Jeffrey I.

2015-01-01

Reading comprehension is a critical building block for effective early literacy development. Many students with autism spectrum disorder demonstrate difficulties in reading comprehension. These difficulties may be attributed to deficits in Theory of Mind, Weak Central Coherence, and Executive Functioning. Given the rise in the number of students…

Clinical Manifestation and a New "ISCU" Mutation in Iron-Sulphur Cluster Deficiency Myopathy

ERIC Educational Resources Information Center

Kollberg, Gittan; Tulinius, Mar; Melberg, Atle; Darin, Niklas; Andersen, Oluf; Holmgren, Daniel; Oldfors, Anders; Holme, Elisabeth

2009-01-01

Myopathy with deficiency of succinate dehydrogenase and aconitase is a recessively inherited disorder characterized by childhood-onset early fatigue, dyspnoea and palpitations on trivial exercise. The disease is non-progressive, but life-threatening episodes of widespread weakness, severe metabolic acidosis and rhabdomyolysis may occur. The…

Nosology and Diagnosis of Rett Syndrome

ERIC Educational Resources Information Center

Matson, Johnny L.; Fodstad, Jill C.; Boisjoli, Jessica A.

2008-01-01

Rett Syndrome is one of the least commonly occurring autism spectrum disorders (ASD), but certainly one of the most devastating. A genetic profile has been identified, but checklists still have an important role for prescreening, especially before expensive genetic testing, and to provide precise strengths and weaknesses with respect to the core…

The Interplay between Executive Control and Motor Functioning in Williams Syndrome

ERIC Educational Resources Information Center

Hocking, Darren R.; Thomas, Daniel; Menant, Jasmine C.; Porter, Melanie A.; Smith, Stuart; Lord, Stephen R.; Cornish, Kim M.

2013-01-01

Previous studies suggest that individuals with Williams syndrome (WS), a rare genetically based neurodevelopmental disorder, show specific weaknesses in visual attention and response inhibition within the visuospatial domain. Here we examine the extent to which impairments in attentional control extend to the visuomotor domain using a…

Working Memory Weaknesses in Students with ADHD: Implications for Instruction

ERIC Educational Resources Information Center

Martinussen, Rhonda; Major, Ashley

2011-01-01

Students with attention deficit hyperactivity disorder (ADHD) are at risk for academic underachievement. Children and youth with ADHD have been found to exhibit impairments on neuropsychological measures of executive functions, including working memory. Working memory is important to attentional control and learning. This article defines working…

Prevalence of spinal disorders and their relationships with age and gender

PubMed Central

Alshami, Ali M.

2015-01-01

Objectives: To establish the period prevalence of spinal disorders referred to physical therapy in a university hospital over a 3-year period, and to determine the relationships of common spinal disorders with patients’ age and gender. Methods: This retrospective study was conducted in the Physical Therapy Department, King Fahd Hospital of the University, Dammam, Saudi Arabia. Computer data of all new electronic referrals from January 2011 to December 2013 were retrieved and reviewed. The computer data included demographic information, referring facility, and diagnosis/disorder. Results: One thousand six hundred and sixty-nine (28.1%) of all referred patients (5929) had spinal disorders. The most common disorders affected the lumbar spine (53.1%) and cervical spine (27.1%), and pain was the most common disorder. Neck pain (60.5%) was more common in patients <30 years old (p<0.001). Cervical spondylosis was common (~30%) in the >30 age groups. Spondylosis and low back pain were more prevalent in women (7.8% and 76.2%) than in men (73.9% and 3.3%). Conclusion: Spinal disorders were common compared with other disorders. Low back pain and neck pain were the most common spinal disorders. Age and gender were weakly related to some of the disorders that affected the lumbar and cervical spine. PMID:25987116

Two-dimensional La2/3Sr4/3MnO4 Manganite Films Probed by Epitaxial Strain and Cation Ordering

NASA Astrophysics Data System (ADS)

Nelson-Cheeseman, Brittany; Santos, Tiffany; Bhattacharya, Anand

2010-03-01

Dimensionality is known to play a central role in the properties of strongly correlated systems. Here we investigate magnetism and transport in thin films of the Ruddlesden-Popper n=1 phase, La1-xSr1+xMnO4. Within this material, the MnO6-octahedra form two-dimensional perovskite sheets separated by an extra rocksalt layer. By fabricating high quality thin films with ozone-assisted molecular beam epitaxy, we study how the effects of epitaxial strain and intentional cation ordering, known as digital synthesis, influence the properties of this 2-dimensional manganite. For example, at the same Mn^3+:Mn^4+ ratio (2:1) as its fully spin-polarized 3D manganite counterpart, this two dimensional analog at x=1/3 only displays a spin glass phase below 20K in bulk. This is believed to result from a competition between superexchange and double exchange, as well as disordered Jahn-Teller distortions. However, in our films we find weak ferromagnetic order up to much higher temperatures in addition to a low temperature spin glass phase. We will discuss how strain and cation order effect the presence of this weak ferromagnetism.

Benefits of Distinguishing between Physical and Social-Verbal Aspects of Behavior: An Example of Generalized Anxiety.

PubMed

Trofimova, Irina; Sulis, William

2016-01-01

Temperament traits and mental illness have been linked to varying degrees of imbalances in neurotransmitter systems of behavior regulation. If a temperament model has been carefully structured to reflect weak imbalances within systems of behavior regulation, then in the presence of mental illness, these profiles should exhibit distinct patterns consistent with symptoms of mental illness. In contrast to other temperament models used in studies of anxiety disorders, the Functional Ensemble of Temperament (FET) model differentiates not only between emotionality traits, but also between traits related to physical, social-verbal and mental aspects of behavior. This paper analyzed the predictions of the FET model, which maps 12 functional aspects of behavior to symptoms of generalized anxiety disorder (GAD) as described in the DSM/ICD. As an example, the paper describes a study of the coupling of sex, age and temperament traits with GAD using the FET framework. The intake records of 116 clients in treatment with confirmed diagnosis of GAD in a private psychological practice were compared using ANOVA against records of 146 healthy clients using their scores on the FET-based questionnaire, in age groups 17-24, 25-45, 46-65. Patients with GAD in all age groups reported significantly lower Social Endurance, Social Tempo, Probabilistic reasoning (but not in physical aspects of behavior) and higher Neuroticism than healthy individuals, however, no effects on the scales of Motor Endurance or Tempo were found. These findings show the benefits of differentiation between motor-physical and social-verbal aspects of behavior in psychological assessment of mental disorders.

The behavioral economics of social anxiety disorder reveal a robust effect for interpersonal traits.

PubMed

Rodebaugh, Thomas L; Tonge, Natasha A; Weisman, Jaclyn S; Lim, Michelle H; Fernandez, Katya C; Bogdan, Ryan

2017-08-01

Recent evidence suggests that reduced generosity among individuals with social anxiety disorder (SAD) in behavioral economic tasks may result from constraint in changing behavior according to interpersonal contingencies. That is, people with SAD may be slower to be more generous when the situation warrants. Conversely, more global effects on generosity may be related to interpersonal vindictiveness, a dimension only somewhat related to SAD. A total of 133 participants, 73 with the generalized form of SAD, completed self-report instruments and a behavioral economic task with simulated interpersonal (friend, romantic partner, stranger) interactions. In a separate visit, friends (n = 88) also came to the lab and rated participants on vindictiveness. Interpersonal vindictiveness was associated with reduced initial and overall giving to simulated friends. SAD predicted a lack of increased giving to a simulated friend, and attenuated an increase in giving to simulated known versus unknown players compared to participants without SAD. Friend-reported vindictiveness predicted in the same direction as diagnosis. However, the findings for SAD were less robust than those for vindictiveness. SAD is perhaps weakly related to behavioral constraint in economic tasks that simulate interpersonal interactions, whereas vindictiveness is strongly related to lower overall generosity as well as (via friend report) behavioral constraint. Further study is needed to better characterize the construct of vindictiveness. Our findings dovetail with the suggestion that SAD is related to impairment in the proposed affiliation and attachment system, but further suggest that direct study of that system may be more fruitful than focusing on disorders. Copyright © 2017 Elsevier Ltd. All rights reserved.

How weak values emerge in joint measurements on cloned quantum systems.

PubMed

Hofmann, Holger F

2012-07-13

A statistical analysis of optimal universal cloning shows that it is possible to identify an ideal (but nonpositive) copying process that faithfully maps all properties of the original Hilbert space onto two separate quantum systems, resulting in perfect correlations for all observables. The joint probabilities for noncommuting measurements on separate clones then correspond to the real parts of the complex joint probabilities observed in weak measurements on a single system, where the measurements on the two clones replace the corresponding sequence of weak measurement and postselection. The imaginary parts of weak measurement statics can be obtained by replacing the cloning process with a partial swap operation. A controlled-swap operation combines both processes, making the complete weak measurement statistics accessible as a well-defined contribution to the joint probabilities of fully resolved projective measurements on the two output systems.

Quantum entanglement in inhomogeneous 1D systems

NASA Astrophysics Data System (ADS)

Ramírez, Giovanni

2018-04-01

The entanglement entropy of the ground state of a quantum lattice model with local interactions usually satisfies an area law. However, in 1D systems some violations may appear in inhomogeneous systems or in random systems. In our inhomogeneous system, the inhomogeneity parameter, h, allows us to tune different regimes where a volumetric violation of the area law appears. We apply the strong disorder renormalization group to describe the maximally entangled state of the system in a strong inhomogeneity regime. Moreover, in a weak inhomogeneity regime, we use a continuum approximation to describe the state as a thermo-field double in a conformal field theory with an effective temperature which is proportional to the inhomogeneity parameter of the system. The latter description also shows that the universal scaling features of this model are captured by a massless Dirac fermion in a curved space-time with constant negative curvature R = h2, providing another example of the relation between quantum entanglement and space-time geometry. The results we discuss here were already published before, but here we present a more didactic exposure of basic concepts of the rainbow system for the students attending the Latin American School of Physics "Marcos Moshinsky" 2017.

Out-of-time-order correlators in finite open systems

NASA Astrophysics Data System (ADS)

Syzranov, S. V.; Gorshkov, A. V.; Galitski, V.

2018-04-01

We study out-of-time-order correlators (OTOCs) of the form for a quantum system weakly coupled to a dissipative environment. Such an open system may serve as a model of, e.g., a small region in a disordered interacting medium coupled to the rest of this medium considered as an environment. We demonstrate that for a system with discrete energy levels the OTOC saturates exponentially ∝∑aie-t /τi+const to a constant value at t →∞ , in contrast with quantum-chaotic systems which exhibit exponential growth of OTOCs. Focusing on the case of a two-level system, we calculate microscopically the decay times τi and the value of the saturation constant. Because some OTOCs are immune to dephasing processes and some are not, such correlators may decay on two sets of parametrically different time scales related to inelastic transitions between the system levels and to pure dephasing processes, respectively. In the case of a classical environment, the evolution of the OTOC can be mapped onto the evolution of the density matrix of two systems coupled to the same dissipative environment.

Preschool anxiety disorders in pediatric primary care: prevalence and comorbidity.

PubMed

Franz, Lauren; Angold, Adrian; Copeland, William; Costello, E Jane; Towe-Goodman, Nissa; Egger, Helen

2013-12-01

We sought to establish prevalence rates and detail patterns of comorbidity for generalized anxiety disorder, separation anxiety disorder, and social phobia in preschool-aged children. The Duke Preschool Anxiety Study, a screen-stratified, cross-sectional study, drew from pediatric primary care and oversampled for children at risk for anxiety. A total of 917 parents of preschool children (aged 2-5 years) completed the Preschool Age Psychiatric Assessment. Generalized anxiety disorder, separation anxiety disorder, and social phobia are common in preschool-aged children attending pediatric primary care. Three-fourths of preschoolers with an anxiety disorder only had a single anxiety disorder. Generalized anxiety disorder displayed the greatest degree of comorbidity: with separation anxiety disorder (odds ratio [OR] = 4.1, 95% CI = 2.0-8.5), social phobia (OR = 6.4, 95% CI = 3.1-13.4), disruptive behavior disorders (OR = 5.1, 95% CI = 1.6-15.8), and depression (OR = 3.7, 95% CI = 1.1-12.4). The weakness of association between generalized anxiety disorder and depression stands in contrast to substantial associations between these 2 disorders reported in older individuals. Attenuated associations in preschool-aged children could translate into clinical opportunities for targeted early interventions, aimed at modifying the developmental trajectory of anxiety disorders. Copyright © 2013 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

Recovery from DSM-IV post-traumatic stress disorder in the WHO World Mental Health surveys.

PubMed

Rosellini, A J; Liu, H; Petukhova, M V; Sampson, N A; Aguilar-Gaxiola, S; Alonso, J; Borges, G; Bruffaerts, R; Bromet, E J; de Girolamo, G; de Jonge, P; Fayyad, J; Florescu, S; Gureje, O; Haro, J M; Hinkov, H; Karam, E G; Kawakami, N; Koenen, K C; Lee, S; Lépine, J P; Levinson, D; Navarro-Mateu, F; Oladeji, B D; O'Neill, S; Pennell, B-E; Piazza, M; Posada-Villa, J; Scott, K M; Stein, D J; Torres, Y; Viana, M C; Zaslavsky, A M; Kessler, R C

2018-02-01

Research on post-traumatic stress disorder (PTSD) course finds a substantial proportion of cases remit within 6 months, a majority within 2 years, and a substantial minority persists for many years. Results are inconsistent about pre-trauma predictors. The WHO World Mental Health surveys assessed lifetime DSM-IV PTSD presence-course after one randomly-selected trauma, allowing retrospective estimates of PTSD duration. Prior traumas, childhood adversities (CAs), and other lifetime DSM-IV mental disorders were examined as predictors using discrete-time person-month survival analysis among the 1575 respondents with lifetime PTSD. 20%, 27%, and 50% of cases recovered within 3, 6, and 24 months and 77% within 10 years (the longest duration allowing stable estimates). Time-related recall bias was found largely for recoveries after 24 months. Recovery was weakly related to most trauma types other than very low [odds-ratio (OR) 0.2-0.3] early-recovery (within 24 months) associated with purposefully injuring/torturing/killing and witnessing atrocities and very low later-recovery (25+ months) associated with being kidnapped. The significant ORs for prior traumas, CAs, and mental disorders were generally inconsistent between early- and later-recovery models. Cross-validated versions of final models nonetheless discriminated significantly between the 50% of respondents with highest and lowest predicted probabilities of both early-recovery (66-55% v. 43%) and later-recovery (75-68% v. 39%). We found PTSD recovery trajectories similar to those in previous studies. The weak associations of pre-trauma factors with recovery, also consistent with previous studies, presumably are due to stronger influences of post-trauma factors.

Pinning by rare defects and effective mobility for elastic interfaces in high dimensions

NASA Astrophysics Data System (ADS)

Cao, Xiangyu; Démery, Vincent; Rosso, Alberto

2018-06-01

The existence of a depinning transition for a high dimensional interface in a weakly disordered medium is controversial. Following Larkin arguments and a perturbative expansion, one expects a linear response with a renormalized mobility . In this paper, we compare these predictions with the exact solution of a fully connected model, which displays a finite critical force . At small disorder, we unveil an intermediary linear regime for characterized by the renormalized mobility . Our results suggest that in high dimension the critical force is always finite and determined by the effect of rare impurities that is missed by the perturbative expansion. However, the perturbative expansion correctly describes an intermediate regime that should be visible at small disorder.

Ergonomic applications to dental practice.

PubMed

Gupta, Shipra

2011-01-01

The term "work-related musculoskeletal disorders (WMSDs)," refers to musculoskeletal disorders to which the work environment contributes significantly, or to musculoskeletal disorders that are made worse or longer lasting by work conditions or workplace risk factors. In recent years, there has been an increase in reporting WMSDs for dental persons. Risk factors of WMSDs with specific reference to dentistry include - stress, poor flexibility, improper positioning, infrequent breaks, repetitive movements, weak postural muscles, prolonged awkward postures and improper adjustment of equipment. Ergonomics is the science of designing jobs, equipment and workplaces to fit workers. Proper ergonomic design is necessary to prevent repetitive strain injuries, which can develop over time and can lead to long-term disability. In this article, 20 strategies to prevent WMSDs in the dental operatory are discussed.

Stochastic Resonance in an Underdamped System with Pinning Potential for Weak Signal Detection

PubMed Central

Zhang, Haibin; He, Qingbo; Kong, Fanrang

2015-01-01

Stochastic resonance (SR) has been proved to be an effective approach for weak sensor signal detection. This study presents a new weak signal detection method based on a SR in an underdamped system, which consists of a pinning potential model. The model was firstly discovered from magnetic domain wall (DW) in ferromagnetic strips. We analyze the principle of the proposed underdamped pinning SR (UPSR) system, the detailed numerical simulation and system performance. We also propose the strategy of selecting the proper damping factor and other system parameters to match a weak signal, input noise and to generate the highest output signal-to-noise ratio (SNR). Finally, we have verified its effectiveness with both simulated and experimental input signals. Results indicate that the UPSR performs better in weak signal detection than the conventional SR (CSR) with merits of higher output SNR, better anti-noise and frequency response capability. Besides, the system can be designed accurately and efficiently owing to the sensibility of parameters and potential diversity. The features also weaken the limitation of small parameters on SR system. PMID:26343662

Stochastic Resonance in an Underdamped System with Pinning Potential for Weak Signal Detection.

PubMed

Zhang, Haibin; He, Qingbo; Kong, Fanrang

2015-08-28

Stochastic resonance (SR) has been proved to be an effective approach for weak sensor signal detection. This study presents a new weak signal detection method based on a SR in an underdamped system, which consists of a pinning potential model. The model was firstly discovered from magnetic domain wall (DW) in ferromagnetic strips. We analyze the principle of the proposed underdamped pinning SR (UPSR) system, the detailed numerical simulation and system performance. We also propose the strategy of selecting the proper damping factor and other system parameters to match a weak signal, input noise and to generate the highest output signal-to-noise ratio (SNR). Finally, we have verified its effectiveness with both simulated and experimental input signals. Results indicate that the UPSR performs better in weak signal detection than the conventional SR (CSR) with merits of higher output SNR, better anti-noise and frequency response capability. Besides, the system can be designed accurately and efficiently owing to the sensibility of parameters and potential diversity. The features also weaken the limitation of small parameters on SR system.

A case of chronic inflammatory demyelinating polyneuropathy presented with unilateral ptosis.

PubMed

Izadi, Sadegh; Karamimagham, Sina; Poursadeghfard, Maryam

2014-01-01

Chronic Inflammatory Demyelinating Polyneuropathy is an autoimmune disease with progressive and relapsing courses. The main clinical presentations are diffuse deep tendon hyporeflexia or areflexia and symmetric proximal-distal muscles weakness. Myasthenia gravis is also an immune mediated disease with fluctuating ocular and bulbar symptoms and sometimes weakness. Although both myasthenia gravis and chronic inflammatory demyelinating polyneuropathy are immune mediated disorders, clinical presentations are obviously different in the two diseases. Herein, we will report a case of chronic inflammatory demyelinating polyneuropathy who presented with isolated unilateral ptosis. Initially, the patient was managed as ocular type of myasthenia gravis, but after progression to general limb weakness and areflexia, the diagnosis of chronic inflammatory demyelinating polyneuropathy was made. Although unilateral ptosis is a typical feature of myasthenia gravis, it may be seen as the first presentation of chronic inflammatory demyelinating polyneuropathy as well which mimics myasthenia gravis disease.

Hereditary sensory ataxic neuropathy associated with proximal muscle weakness in the lower extremities.

PubMed

Murakami, Tatsufumi; Fukai, Yuta; Rikimaru, Mitsue; Henmi, Shoji; Ohsawa, Yutaka; Sunada, Yoshihide

2010-04-15

We describe three patients from the same family with hereditary sensory ataxic neuropathy followed by proximal muscle weakness in the lower extremities. Sensory ataxic gait began as an initial symptom when patients were in their 50s. Mild proximal weakness in the lower extremities appeared several years later. Serum creatine kinase was mildly elevated. Nerve conduction studies revealed sensory dominant axonal neuropathy, and short sensory evoked potentials showed involvement of the sensory nerve axon, dorsal root ganglia and posterior funiculus of the spinal cord. Needle electromyography showed fibrillation, positive sharp waves, and multiple giant motor unit potentials, suggesting the involvement of anterior horn motor neurons or the anterior root. Autosomal recessive inheritance was considered, because of consanguinity. The disorder described here may be a new clinical entity with unique clinical manifestations. Copyright 2009 Elsevier B.V. All rights reserved.

Hyperthyroidism: an unusual case presentation.

PubMed

Scripture, D L

1998-02-01

Hyperthyroidism is the most common disorder of the thyroid. Patients typically present with complaints consistent with a hypermetabolic state, including nervousness, weight loss, heat intolerance, palpitations, irritability, and tremor. This case report reviews a 34-year-old woman who presented with unilateral upper extremity weakness, weight gain, and an episode of atrial fibrillation, the latter coinciding with a 36-hour lack of sleep and excess alcohol and caffeine intake. Although an extensive neurologic evaluation failed to identify any abnormality, the patient's laboratory analysis revealed elevations in thyroxine (T4) and triiodothyronine (T3) levels with unsuppressed thyroid-stimulating hormone levels. Subsequent treatment with the antithyroid drug methimazole (Tapazole) provided complete relief of symptoms. This case report illustrates how health care providers can be diverted to pursue a neurologic etiology when muscle weakness presents as a unilateral symptom. Plausible alternative causes for muscle weakness and other symptoms are presented.

The myasthenic patient in crisis: an update of the management in Neurointensive Care Unit.

PubMed

Godoy, Daniel Agustin; Mello, Leonardo Jardim Vaz de; Masotti, Luca; Di Napoli, Mario

2013-09-01

Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular transmission leading to generalized or localized muscle weakness due most frequently to the presence of autoantibodies against acetylcholine receptors in the postsynaptic motor end-plate. Myasthenic crisis (MC) is a complication of MG characterized by worsening muscle weakness, resulting in respiratory failure that requires intubation and mechanical ventilation. It also includes postsurgical patients, in whom exacerbation of muscle weakness from MG causes a delay in extubation. MC is a very important, serious, and reversible neurological emergency that affects 20-30% of the myasthenic patients, usually within the first year of illness and maybe the debut form of the disease. Most patients have a predisposing factor that triggers the crisis, generally an infection of the respiratory tract. Immunoglobulins, plasma exchange, and steroids are the cornerstones of immunotherapy. Today with the modern neurocritical care, mortality rate of MC is less than 5%.

Disturbances of automatic gait control mechanisms in higher level gait disorder.

PubMed

Danoudis, Mary; Ganesvaran, Ganga; Iansek, Robert

2016-07-01

The underlying mechanisms responsible for the gait changes in frontal gait disorder (FGD), a form of higher level gait disorders, are poorly understood. We investigated the relationship between stride length and cadence (SLCrel) in people with FGD (n=15) in comparison to healthy older adults (n=21) to improve our understanding of the changes to gait in FGD. Gait data was captured using an electronic walkway system as participants walked at five self-selected speed conditions: preferred, very slow, slow, fast and very fast. Linear regression was used to determine the strength of the relationship (R(2)), slope and intercept. In the FGD group 9 participants had a strong SLCrel (linear group) (R(2)>0.8) and 6 a weak relationship (R(2)<0.8) (nonlinear group). The linear FGD group did not differ to healthy control for slope (p>0.05) but did have a lower intercept (p<0.001). The linear FGD group modulated gait speed by adjusting stride length and cadence similar to controls whereas the nonlinear FGD participants adjusted stride length but not cadence similar to controls. The non-linear FGD group had greater disturbance to their gait, poorer postural control and greater fear of falling compared to the linear FGD group. Investigation of the SLCrel resulted in new insights into the underlying mechanisms responsible for the gait changes found in FGD. The findings suggest stride length regulation was disrupted in milder FGD but as the disorder worsened, cadence control also became disordered resulting in a break down in the relationship between stride length and cadence. Copyright © 2016 Elsevier B.V. All rights reserved.

Transgenic Mouse Models of Childhood Onset Psychiatric Disorders

PubMed Central

Robertson, Holly R.; Feng, Guoping

2011-01-01

Childhood onset psychiatric disorders, such as Attention Deficit Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD), Mood Disorders, Obsessive Compulsive Spectrum Disorders (OCSD), and Schizophrenia (SZ), affect many school age children leading to a lower quality of life, including difficulties in school and personal relationships that persists into adulthood. Currently, the causes of these psychiatric disorders are poorly understood resulting in difficulty diagnosing affected children, and insufficient treatment options. Family and twin studies implicate a genetic contribution for ADHD, ASD, Mood Disorders, OCSD, and SZ. Identification of candidate genes and chromosomal regions associated with a particular disorder provide targets for directed research, and understanding how these genes influence the disease state will provide valuable insights for improving the diagnosis and treatment of children with psychiatric disorders. Animal models are one important approach in the study of human diseases, allowing for the use of a variety of experimental approaches to dissect the contribution of a specific chromosomal or genetic abnormality in human disorders. While it is impossible to model an entire psychiatric disorder in a single animal model, these models can be extremely valuable in dissecting out the specific role of a gene, pathway, neuron subtype, or brain region in a particular abnormal behavior. In this review we discuss existing transgenic mouse models for childhood onset psychiatric disorders. We compare the strength and weakness of various transgenic animal models proposed for each of the common childhood onset psychiatric disorders, and discuss future directions for the study of these disorders using cutting-edge genetic tools. PMID:21309772

Do Executive and Reactive Disinhibition Mediate the Effects of Familial Substance Use Disorders on Adolescent Externalizing Outcomes?

PubMed Central

Handley, Elizabeth D.; Chassin, Laurie; Haller, Moira M.; Bountress, Kaitlin E.; Dandreaux, Danielle; Beltran, Iris

2011-01-01

The present study examined the potential mediating roles of executive and reactive disinhibition in predicting conduct problems, ADHD symptoms, and substance use among adolescents with and without a family history of substance use disorders. Using data from 247 high-risk adolescents, parents, and grandparents, structural equation modeling indicated that reactive disinhibition, as measured by sensation seeking, mediated the effect of familial drug use disorders on all facets of the adolescent externalizing spectrum. Executive disinhibition, as measured by response disinhibition, spatial short term memory, and “trait” impulsivity, was associated with ADHD symptoms. Moreover, although executive functioning weakness were unrelated to familial substance use disorders, adolescents with familial alcohol use disorders were at risk for “trait” impulsivity marked by a lack of planning. These results illustrate the importance of “unpacking” the broad temperament style of disinhibition and of studying the processes that underlie the commonality among facets of the externalizing spectrum and processes that that predict specific externalizing outcomes. PMID:21668077

Myasthenia and related disorders of the neuromuscular junction.

PubMed

Spillane, Jennifer; Beeson, David J; Kullmann, Dimitri M

2010-08-01

Our understanding of transmission at the neuromuscular junction has increased greatly in recent years. We now recognise a wide variety of autoimmune and genetic diseases that affect this specialised synapse, causing muscle weakness and fatigue. These disorders greatly affect quality of life and rarely can be fatal. Myasthenia gravis is the most common disorder and is most commonly caused by autoantibodies targeting postsynaptic acetylcholine receptors. Antibodies to muscle-specific kinase (MuSK) are detected in a variable proportion of the remainder. Treatment is symptomatic and immunomodulatory. Lambert-Eaton myasthenic syndrome is caused by antibodies to presynaptic calcium channels, and approximately 50% of cases are paraneoplastic, most often related to small cell carcinoma of the lung. Botulism is an acquired disorder caused by neurotoxins produced by Clostridium botulinum, impairing acetylcholine release into the synaptic cleft. In addition, several rare congenital myasthenic syndromes have been identified, caused by inherited defects in presynaptic, synaptic basal lamina and postsynaptic proteins necessary for neuromuscular transmission. This review focuses on recent advances in the diagnosis and treatment of these disorders.

Who Gets Fungal Infections?

MedlinePlus

... can also happen in people without weak immune systems Fungal infections that are not life-threatening, such ... to cause an infection. People with weak immune systems Infections that happen because a person’s immune system ...

The New Multi-Ministry Response to Conduct Problems: A SWOT Analysis

ERIC Educational Resources Information Center

Stanley, Peter

2008-01-01

"The Inter-agency Plan for Conduct Disorder/Severe Antisocial Behaviour 2007-2012" (Ministry of Social Development, 2007) is assessed according to the SWOT dimensions of strengths, weaknesses, opportunities and threats. The document is one of the most important statements for the social services in New Zealand because of the primacy that…

Orientation Perception in Williams Syndrome: Discrimination and Integration

ERIC Educational Resources Information Center

Palomares, Melanie; Landau, Barbara; Egeth, Howard

2009-01-01

Williams Syndrome (WS) is a rare neurodevelopmental disorder, which stems from a genetic deletion on chromosome 7 and causes a profound weakness in visuospatial cognition. Our current study explores how orientation perception may contribute to the visuospatial deficits in WS. In Experiment 1, we found that WS individuals and normal 3-4 year olds…

Neurocognitive Features of Attention Deficit Hyperactivity Disorder in a Non-Clinical Adult Sample

DTIC Science & Technology

2004-01-01

samples. Whether these cognitive weaknesses are associated with ADHD symptoms in non-clinical samples is unknown. The current study examined the...relationship between ADHD symptoms and cognitive performance in a non-clinical adult sample of 75 men and women (ages 20 to 49). Self-report measures of ADHD

Autistic Traits and Cognitive Performance in Young People with Mild Intellectual Impairment

ERIC Educational Resources Information Center

Harris, Jonathan M.; Best, Catherine S.; Moffat, Vivien J.; Spencer, Michael D.; Philip, Ruth C. M.; Power, Michael J.; Johnstone, Eve C.

2008-01-01

Cognitive performance and the relationship between theory of mind (TOM), weak central coherence and executive function were investigated in a cohort of young people with additional learning needs. Participants were categorized by social communication questionnaire score into groups of 10 individuals within the autistic spectrum disorder (ASD)…

Learning to Read in Williams Syndrome and Down Syndrome: Syndrome-Specific Precursors and Developmental Trajectories

ERIC Educational Resources Information Center

Steele, Ann; Scerif, Gaia; Cornish, Kim; Karmiloff-Smith, Annette

2013-01-01

Background: In typical development, early reading is underpinned by language skills, like vocabulary and phonological awareness (PA), as well as taught skills like letter knowledge. Less is understood about how early reading develops in children with neurodevelopmental disorders who display specific profiles of linguistic strengths and weaknesses,…

Relationship between Fatigue and Gait Abnormality in Joint Hypermobility Syndrome/Ehlers-Danlos Syndrome Hypermobility Type

ERIC Educational Resources Information Center

Celletti, Claudia; Galli, Manuela; Cimolin, Veronica; Castori, Marco; Albertini, Giorgio; Camerota, Filippo

2012-01-01

Ehlers-Danlos syndrome (EDS) is a clinically and genetically heterogeneous group of inherited connective tissue disorders characterised by joint hypermobility, skin hyperextensibility and tissue fragility. It has recently been shown that muscle weakness occurs frequently in EDS, and that fatigue is a common and clinically important symptom. The…

Understanding the Mind of a Student with Autism in Music Class

ERIC Educational Resources Information Center

Hourigan, Ryan M.; Hammel, Alice M.

2017-01-01

This article offers a unique look into the cognitive processes of students with autism spectrum disorder in music classrooms. Concepts include theory of mind, weak central coherence, executive function, joint attention, and social attention. Behavior implications are also examined. Specific examples of support tools for the music classroom are…

Superior haptic-to-visual shape matching in autism spectrum disorders.

PubMed

Nakano, Tamami; Kato, Nobumasa; Kitazawa, Shigeru

2012-04-01

A weak central coherence theory in autism spectrum disorder (ASD) proposes that a cognitive bias toward local processing in ASD derives from a weakness in integrating local elements into a coherent whole. Using this theory, we hypothesized that shape perception through active touch, which requires sequential integration of sensorimotor traces of exploratory finger movements into a shape representation, would be impaired in ASD. Contrary to our expectation, adults with ASD showed superior performance in a haptic-to-visual delayed shape-matching task compared to adults without ASD. Accuracy in discriminating haptic lengths or haptic orientations, which lies within the somatosensory modality, did not differ between adults with ASD and adults without ASD. Moreover, this superior ability in inter-modal haptic-to-visual shape matching was not explained by the score in a unimodal visuospatial rotation task. These results suggest that individuals with ASD are not impaired in integrating sensorimotor traces into a global visual shape and that their multimodal shape representations and haptic-to-visual information transfer are more accurate than those of individuals without ASD. Copyright © 2012 Elsevier Ltd. All rights reserved.

Role of spin diffusion in current-induced domain wall motion for disordered ferromagnets

NASA Astrophysics Data System (ADS)

Akosa, Collins Ashu; Kim, Won-Seok; Bisig, André; Kläui, Mathias; Lee, Kyung-Jin; Manchon, Aurélien

2015-03-01

Current-induced spin transfer torque and magnetization dynamics in the presence of spin diffusion in disordered magnetic textures is studied theoretically. We demonstrate using tight-binding calculations that weak, spin-conserving impurity scattering dramatically enhances the nonadiabaticity. To further explore this mechanism, a phenomenological drift-diffusion model for incoherent spin transport is investigated. We show that incoherent spin diffusion indeed produces an additional spatially dependent torque of the form ˜∇2[m ×(u .∇ ) m ] +ξ ∇2[(u .∇ ) m ] , where m is the local magnetization direction, u is the direction of injected current, and ξ is a parameter characterizing the spin dynamics (precession, dephasing, and spin-flip). This torque, which scales as the inverse square of the domain wall width, only weakly enhances the longitudinal velocity of a transverse domain wall but significantly enhances the transverse velocity of vortex walls. The spatial-dependent spin transfer torque uncovered in this study is expected to have significant impact on the current-driven motion of abrupt two-dimensional textures such as vortices, skyrmions, and merons.

Local vibrations in disordered solids studied via single-molecule spectroscopy: Comparison with neutron, nuclear, Raman scattering, and photon echo data

NASA Astrophysics Data System (ADS)

Vainer, Yu. G.; Naumov, A. V.; Kador, L.

2008-06-01

The energy spectrum of low-frequency vibrational modes (LFMs) in three disordered organic solids—amorphous polyisobutylene (PIB), toluene and deuterated toluene glasses, weakly doped with fluorescent chromophore molecules of tetra-tert-butylterrylene (TBT) has been measured via single-molecule (SM) spectroscopy. Analysis of the individual temperature dependences of linewidths of single TBT molecules allowed us to determine the values of the vibrational mode frequencies and the SM-LFM coupling constants for vibrations in the local environment of the molecules. The measured LFM spectra were compared with the “Boson peak” as measured in pure PIB by inelastic neutron scattering, in pure toluene glass by low-frequency Raman scattering, in doped toluene glass by nuclear inelastic scattering, and with photon echo data. The comparative analysis revealed close agreement between the spectra of the local vibrations as measured in the present study and the literature data of the Boson peak in PIB and toluene. The analysis has also the important result that weak doping of the disordered matrices with nonpolar probe molecules whose chemical composition is similar to that of the matrix molecules does not influence the observed vibrational dynamics markedly. The experimental data displaying temporal stability on the time scale of a few hours of vibrational excitation parameters in local surroundings was obtained for the first time both for polymer and molecular glass.

Superconductivity in highly disordered NbN nanowires.

PubMed

Arutyunov, K Yu; Ramos-Álvarez, A; Semenov, A V; Korneeva, Yu P; An, P P; Korneev, A A; Murphy, A; Bezryadin, A; Gol'tsman, G N

2016-11-25

The topic of superconductivity in strongly disordered materials has attracted significant attention. These materials appear to be rather promising for fabrication of various nanoscale devices such as bolometers and transition edge sensors of electromagnetic radiation. The vividly debated subject of intrinsic spatial inhomogeneity responsible for the non-Bardeen-Cooper-Schrieffer relation between the superconducting gap and the pairing potential is crucial both for understanding the fundamental issues of superconductivity in highly disordered superconductors, and for the operation of corresponding nanoelectronic devices. Here we report an experimental study of the electron transport properties of narrow NbN nanowires with effective cross sections of the order of the debated inhomogeneity scales. The temperature dependence of the critical current follows the textbook Ginzburg-Landau prediction for the quasi-one-dimensional superconducting channel I c  ∼ (1-T/T c ) 3/2 . We find that conventional models based on the the phase slip mechanism provide reasonable fits for the shape of R(T) transitions. Better agreement with R(T) data can be achieved assuming the existence of short 'weak links' with slightly reduced local critical temperature T c . Hence, one may conclude that an 'exotic' intrinsic electronic inhomogeneity either does not exist in our structures, or, if it does exist, it does not affect their resistive state properties, or does not provide any specific impact distinguishable from conventional weak links.

Cognitive subtypes of mathematics learning difficulties in primary education.

PubMed

Bartelet, Dimona; Ansari, Daniel; Vaessen, Anniek; Blomert, Leo

2014-03-01

It has been asserted that children with mathematics learning difficulties (MLD) constitute a heterogeneous group. To date, most researchers have investigated differences between predefined MLD subtypes. Specifically MLD children are frequently categorized a priori into groups based on the presence or absence of an additional disorder, such as a reading disorder, to examine cognitive differences between MLD subtypes. In the current study 226 third to six grade children (M age=131 months) with MLD completed a selection of number specific and general cognitive measures. The data driven approach was used to identify the extent to which performance of the MLD children on these measures could be clustered into distinct groups. In particular, after conducting a factor analysis, a 200 times repeated K-means clustering approach was used to classify the children's performance. Results revealed six distinguishable clusters of MLD children, specifically (a) a weak mental number line group, (b) weak ANS group, (c) spatial difficulties group, (d) access deficit group, (e) no numerical cognitive deficit group and (f) a garden-variety group. These findings imply that different cognitive subtypes of MLD exist and that these can be derived from data-driven approaches to classification. These findings strengthen the notion that MLD is a heterogeneous disorder, which has implications for the way in which intervention may be tailored for individuals within the different subtypes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Statistics of transmission eigenvalues in two-dimensional quantum cavities: Ballistic versus stochastic scattering

NASA Astrophysics Data System (ADS)

Rotter, Stefan; Aigner, Florian; Burgdörfer, Joachim

2007-03-01

We investigate the statistical distribution of transmission eigenvalues in phase-coherent transport through quantum dots. In two-dimensional ab initio simulations for both clean and disordered two-dimensional cavities, we find markedly different quantum-to-classical crossover scenarios for these two cases. In particular, we observe the emergence of “noiseless scattering states” in clean cavities, irrespective of sharp-edged entrance and exit lead mouths. We find the onset of these “classical” states to be largely independent of the cavity’s classical chaoticity, but very sensitive with respect to bulk disorder. Our results suggest that for weakly disordered cavities, the transmission eigenvalue distribution is determined both by scattering at the disorder potential and the cavity walls. To properly account for this intermediate parameter regime, we introduce a hybrid crossover scheme, which combines previous models that are valid in the ballistic and the stochastic limit, respectively.

Behavioral therapy for Tourette syndrome and chronic tic disorders

PubMed Central

Woods, Douglas; Ganos, Christos

2017-01-01

Abstract Purpose of review: To summarize behavioral interventions for the treatment of primary tic disorders. Recent findings: Although tics were attributed to a disordered weak volition, the shift towards neurobiological models of tic disorders also transformed nonpharmacologic treatment practices. Current international guidelines recommend habit reversal training, comprehensive behavioral intervention, and exposure and response prevention as first-line therapies for tics. Appropriate patient selection, including age and presence of comorbidities, are salient clinical features that merit consideration. Evidence for further behavioral interventions is also presented. Summary: Currently recommended behavioral interventions view tics as habitual responses that may be further strengthened through negative reinforcement. Although availability and costs related to these interventions may limit their effect, Internet-based and telehealth approaches may facilitate wide accessibility. Novel nonpharmacologic treatments that take different approaches, such as autonomic modulation or attention-based interventions, may also hold therapeutic promise. PMID:29185535

Muscle-Bone Interactions in Pediatric Bone Diseases.

PubMed

Veilleux, Louis-Nicolas; Rauch, Frank

2017-10-01

Here, we review the skeletal effects of pediatric muscle disorders as well as muscle impairment in pediatric bone disorders. When starting in utero, muscle disorders can lead to congenital multiple contractures. Pediatric-onset muscle weakness such as cerebral palsy, Duchenne muscular dystrophy, spinal muscular atrophy, or spina bifida typically are associated with small diameter of long-bone shafts, low density of metaphyseal bone, and increased fracture incidence in the lower extremities, in particular, the distal femur. Primary bone diseases can affect muscles through generic mechanisms, such as decreased physical activity or in disease-specific ways. For example, the collagen defect underlying the bone fragility of osteogenesis imperfecta may also affect muscle force generation or transmission. Transforming growth factor beta released from bone in Camurati Engelman disease may decrease muscle function. Considering muscle-bone interactions does not only contribute to the understanding of musculoskeletal disorders but also can identify new targets for therapeutic interventions.

Stereotypic behavior in nonhuman primates as a model for the human condition.

PubMed

Lutz, Corrine K

2014-01-01

Stereotypies that develop spontaneously in nonhuman primates can provide an effective model for repetitive stereotyped behavior in people with neurodevelopmental or obsessive-compulsive disorders. The behaviors are similar in form, are similarly affected by environmental conditions, and are improved with similar treatment methods such as enrichment, training, and drug therapy. However, because of a greater number of commonalities in these factors, nonhuman primates may serve as a better model for stereotyped behavior in individuals with autism or intellectual disability than for compulsions in individuals with obsessive-compulsive disorder. Because animal models may not be exact in all features of the disorder being studied, it is important to investigate the strengths and weaknesses of using a nonhuman primate model for stereotyped behavior in people with psychological disorders. © The Author 2014. Published by Oxford University Press on behalf of the Institute for Laboratory Animal Research. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Dimensions of Oppositional Defiant Disorder in Young Children: Heterotypic Continuity with Anxiety and Depression

PubMed Central

Lavigne, John V.; Gouze, Karen R.; Bryant, Fred B.; Hopkins, Joyce

2014-01-01

There are distinct dimensions of Oppositional Defiant Disorder (ODD) that have been associated with symptoms of other disorders (heterotypic continuity). The present study compared the heterotypic continuity of a two-factor (Pitt-2) model and the three-factor model incorporated into DSM-5 with symptoms of anxiety and depression. Participants were a diverse community sample of 796 children (38.8% minority, 49.1% boys) assessed at ages 4, 5 and 6 years. Symptoms were assessed with the dimensional scales of the Diagnostic Interview Schedule for Children-Young Child version and the Child Symptom Inventory. Dimensions of both the two- and three-factor DSM-5 models were associated with later symptoms of anxiety and depression. The association, however, was weak when accounting for initial levels of internalizing symptoms: thus there was little evidence for the unique contributions of ODD dimensions to symptoms of subsequent internalizing disorders for either model. PMID:24497230

Guillain-Barré Syndrome after Coronary Artery Bypass Graft Surgery: a Case Report.

PubMed

Hekmat, Manouchehr; Ghaderi, Hamid; Foroughi, Mahnoosh; Mirjafari, S Adeleh

2016-01-01

Guillain-Barre syndrome is a neurologic disorder that may appear after infection or major surgery. Guillain-Barré syndrome following cardiac surgery is rare and only based on case reports, and we review all of the published cases. A 52-year-old man after 5 months suffering from chest pain was referred to our hospital and underwent coronary artery bypass graft for 3 vessel disease. The patient was discharged without complication on the 5th postoperative day. He presented Guillain-Barré syndrome after 12 months. He has not completely recovered weakness of upper extremities grade 4/5 with atrophy of both upper extremities remains after 18 months. This disorder is similar to classic GBS. It is important to be alert to de novo autoimmune neurological disorders after cardiac surgery. These disorders are similar to classic autoimmune disease and treated with standard therapies.

Partial regularity of weak solutions to a PDE system with cubic nonlinearity

NASA Astrophysics Data System (ADS)

Liu, Jian-Guo; Xu, Xiangsheng

2018-04-01

In this paper we investigate regularity properties of weak solutions to a PDE system that arises in the study of biological transport networks. The system consists of a possibly singular elliptic equation for the scalar pressure of the underlying biological network coupled to a diffusion equation for the conductance vector of the network. There are several different types of nonlinearities in the system. Of particular mathematical interest is a term that is a polynomial function of solutions and their partial derivatives and this polynomial function has degree three. That is, the system contains a cubic nonlinearity. Only weak solutions to the system have been shown to exist. The regularity theory for the system remains fundamentally incomplete. In particular, it is not known whether or not weak solutions develop singularities. In this paper we obtain a partial regularity theorem, which gives an estimate for the parabolic Hausdorff dimension of the set of possible singular points.

Weak-value amplification as an optimal metrological protocol

NASA Astrophysics Data System (ADS)

Alves, G. Bié; Escher, B. M.; de Matos Filho, R. L.; Zagury, N.; Davidovich, L.

2015-06-01

The implementation of weak-value amplification requires the pre- and postselection of states of a quantum system, followed by the observation of the response of the meter, which interacts weakly with the system. Data acquisition from the meter is conditioned to successful postselection events. Here we derive an optimal postselection procedure for estimating the coupling constant between system and meter and show that it leads both to weak-value amplification and to the saturation of the quantum Fisher information, under conditions fulfilled by all previously reported experiments on the amplification of weak signals. For most of the preselected states, full information on the coupling constant can be extracted from the meter data set alone, while for a small fraction of the space of preselected states, it must be obtained from the postselection statistics.

[Hypoglycaemic periodic paralysis in hyperthyroidism patients].

PubMed

Kratochvíl, J; Masopust, J; Martínková, V; Charvát, J

2008-11-01

Hypokalemic periodic paralysis (HPP) is a rare disorder characterised by acute, potentially fatal atacks of muscle weakness or paralysis. Massive shift of potassium into cells is caused by elevated levels of insulin and catecholamines in the blood. Hypophosphatemia and hypomagnesemia may be also present. Acidobasic status usually is not impaired. HPP occurs as familiar (caused by ion channels inherited defects) or acquired (in patients with hyperthyroidism). On the basis of two clinical cases we present a review of hypokalemic periodic paralysis in hyperthyroid patients. We discuss patogenesis, clinical and laboratory findings as well as the principles of prevention and treatment of this rare disorder.

Disorder effects in the evolution from BCS to BEC superfluidity

NASA Astrophysics Data System (ADS)

Han, Li; de Melo, Carlos A. R. Sa

2009-03-01

We discuss the effects of disorder on the critical temperature of superfluids during the evolution from BCS to BEC. For s-wave superfluids we find that the critical temperature is weakly affected by disorder in the BCS regime as described in Anderson’s theorem, even less affected by disorder at zero chemical potential (near unitarity), but strongly affected by disorder in the BEC regime, where Anderson's theorem does not apply. This suggests that the superfluid is more robust to the effects of disorder at the interaction parameter where the chemical potential vanishes (close to unitarity). We construct a three dimensional phase diagram of critical temperature, disorder and interaction parameter [1], and show that there are regions of localized superfluidity, as well as insulating regions due to Anderson localization of fermions (BCS regime) and molecular bosons (BEC regime). The phase diagram for higher angular momentum (e.g. p-wave and d-wave) is also analyzed, where the effects of disorder are much more dramatic in the BCS regime in comparison to the s-wave case because pair breaking is strong, while the disorder effects in BEC regime are similar to what occurs in the s-wave case. [1] Li Han, C. A. R. Sa de Melo, arXiv:0812.xxxx

Neurogenic Orofacial Weakness and Speech in Adults With Dysarthria

PubMed Central

Makashay, Matthew J.; Helou, Leah B.; Clark, Heather M.

2017-01-01

Purpose This study compared orofacial strength between adults with dysarthria and neurologically normal (NN) matched controls. In addition, orofacial muscle weakness was examined for potential relationships to speech impairments in adults with dysarthria. Method Matched groups of 55 adults with dysarthria and 55 NN adults generated maximum pressure (Pmax) against an air-filled bulb during lingual elevation, protrusion and lateralization, and buccodental and labial compressions. These orofacial strength measures were compared with speech intelligibility, perceptual ratings of speech, articulation rate, and fast syllable-repetition rate. Results The dysarthria group demonstrated significantly lower orofacial strength than the NN group on all tasks. Lingual strength correlated moderately and buccal strength correlated weakly with most ratings of speech deficits. Speech intelligibility was not sensitive to dysarthria severity. Individuals with severely reduced anterior lingual elevation Pmax (< 18 kPa) had normal to profoundly impaired sentence intelligibility (99%–6%) and moderately to severely impaired speech (26%–94% articulatory imprecision; 33%–94% overall severity). Conclusions Results support the presence of orofacial muscle weakness in adults with dysarthrias of varying etiologies but reinforce tenuous links between orofacial strength and speech production disorders. By examining individual data, preliminary evidence emerges to suggest that speech, but not necessarily intelligibility, is likely to be impaired when lingual weakness is severe. PMID:28763804

Association between the Rorschach Ego Impairment Index and the Level of Personality Organization interview assessment in depressive and anxiety disorder patients.

PubMed

Valkonen, Harri; Lindfors, Olavi; Knekt, Paul

2012-12-30

The level of personality functioning, relevant for treatment planning, can be evaluated by the Rorschach Comprehensive System (CS) Ego Impairment Index-2 (EII-2) and by interview assessment of the severity of personality pathology. However, few studies on the association between these assessment methods have been reported. This study examines the strength of association between the EII-2 and its subcomponents with the interview-based Level of Personality Organization (LPO) assessment scale, and investigates their mutual associations with psychiatric symptoms, diagnoses, and history. Altogether, 315 mood or anxiety disorder outpatients without severe personality pathology were assessed with the LPO and tested with the CS, on which the EII-2 and its subcomponents (FQ-, WSum6, Critical contents, M-, PHR, GHR, and R) were calculated. Significant, but weak association between the EII-2 and the LPO was found. The WSum6, a measure of thought disorder, was the only EII-2 subcomponent significantly associated with the LPO. Both measures were consistently associated with psychiatric symptoms, diagnoses and history. The findings partially support the EII-2 and the LPO as consistently associated, relatively independent measures of the severity of personality pathology. More research on the incremental benefits of the measures is needed in clinical populations, covering non-severe and complex psychopathology. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Neuropsychological function and memory suppression in conversion disorder.

PubMed

Brown, Laura B; Nicholson, Timothy R; Aybek, Selma; Kanaan, Richard A; David, Anthony S

2014-09-01

Conversion disorder (CD) is a condition where neurological symptoms, such as weakness or sensory disturbance, are unexplained by neurological disease and are presumed to be of psychological origin. Contemporary theories of the disorder generally propose dysfunctional frontal control of the motor or sensory systems. Classical (Freudian) psychodynamic theory holds that the memory of stressful life events is repressed. Little is known about the frontal (executive) function of these patients, or indeed their general neuropsychological profile, and psychodynamic theories have been largely untested. This study aimed to investigate neuropsychological functioning in patients with CD, focusing on executive and memory function. A directed forgetting task (DFT) using words with variable emotional valence was also used to investigate memory suppression. 21 patients and 36 healthy controls completed a battery of neuropsychological tests and patients had deficits in executive function and auditory-verbal (but not autobiographical) memory. The executive deficits were largely driven by differences in IQ, anxiety and mood between the groups. A subgroup of 11 patients and 28 controls completed the DFT and whilst patients recalled fewer words overall than controls, there were no significant effects of directed forgetting or valence. This study provides some limited support for deficits in executive, and to a lesser degree, memory function in patients with CD, but did not find evidence of altered memory suppression to support the psychodynamic theory of repression. © 2013 The British Psychological Society.

Perceptual Integration Deficits in Autism Spectrum Disorders Are Associated with Reduced Interhemispheric Gamma-Band Coherence.

PubMed

Peiker, Ina; David, Nicole; Schneider, Till R; Nolte, Guido; Schöttle, Daniel; Engel, Andreas K

2015-12-16

The integration of visual details into a holistic percept is essential for object recognition. This integration has been reported as a key deficit in patients with autism spectrum disorders (ASDs). The weak central coherence account posits an altered disposition to integrate features into a coherent whole in ASD. Here, we test the hypothesis that such weak perceptual coherence may be reflected in weak neural coherence across different cortical sites. We recorded magnetoencephalography from 20 adult human participants with ASD and 20 matched controls, who performed a slit-viewing paradigm, in which objects gradually passed behind a vertical or horizontal slit so that only fragments of the object were visible at any given moment. Object recognition thus required perceptual integration over time and, in case of the horizontal slit, also across visual hemifields. ASD participants were selectively impaired in the horizontal slit condition, indicating specific difficulties in long-range synchronization between the hemispheres. Specifically, the ASD group failed to show condition-related enhancement of imaginary coherence between the posterior superior temporal sulci in both hemispheres during horizontal slit-viewing in contrast to controls. Moreover, local synchronization reflected in occipitocerebellar beta-band power was selectively reduced for horizontal compared with vertical slit-viewing in ASD. Furthermore, we found disturbed connectivity between right posterior superior temporal sulcus and left cerebellum. Together, our results suggest that perceptual integration deficits co-occur with specific patterns of abnormal global and local synchronization in ASD. The weak central coherence account proposes a tendency of individuals with autism spectrum disorders (ASDs) to focus on details at the cost of an integrated coherent whole. Here, we provide evidence, at the behavioral and the neural level, that visual integration in object recognition is impaired in ASD, when details had to be integrated across both visual hemifields. We found enhanced interhemispheric gamma-band coherence in typically developed participants when communication between cortical hemispheres was required by the task. Importantly, participants with ASD failed to show this enhanced coherence between bilateral posterior superior temporal sulci. The findings suggest that visual integration is disturbed at the local and global synchronization scale, which might bear implications for object recognition in ASD. Copyright © 2015 the authors 0270-6474/15/3516352-10$15.00/0.

Nonlinear conductance in weakly disordered mesoscopic wires: Interaction and magnetic field asymmetry

NASA Astrophysics Data System (ADS)

Texier, Christophe; Mitscherling, Johannes

2018-02-01

We study the nonlinear conductance G ˜∂2I /∂ V2|V =0 in coherent quasi-one-dimensional weakly disordered metallic wires. Our analysis is based on the scattering approach and includes the effect of Coulomb interaction. The nonlinear conductance correlations can be related to integrals of two fundamental correlation functions: the correlator of functional derivatives of the conductance and the correlator of injectivities (the injectivity is the contribution to the local density of states of eigenstates incoming from one contact). These correlators are obtained explicitly by using diagrammatic techniques for weakly disordered metals. In a coherent wire of length L , we obtain rms (G )≃0.006 ETh-1 (and =0 ), where ETh=ℏ D /L2 is the Thouless energy of the wire and D the diffusion constant; the small dimensionless factor results from screening, i.e., cannot be obtained within a simple theory for noninteracting electrons. Electronic interactions are also responsible for an asymmetry under magnetic field reversal; the antisymmetric part of the nonlinear conductance (at high magnetic field) being much smaller than the symmetric one, rms (Ga)≃0.001 (gETh) -1 , where g ≫1 is the dimensionless (linear) conductance of the wire. In a weakly coherent wire (i.e., Lφ≪L , where Lφ is the phase coherence length), the nonlinear conductance is of the same order as the result G0 of a free electron calculation (although screening again strongly reduces the dimensionless prefactor); we get G ˜G0˜(Lφ/L ) 7 /2ETh-1 , while the antisymmetric part (at high magnetic field) now behaves as Ga˜(Lφ/L ) 11 /2(gETh) -1≪G . The effect of thermal fluctuations is studied: when the thermal length LT=√{ℏ D /kBT } is the smallest length scale, LT≪Lφ≪L , the free electron result G0˜(LT/L ) 3(Lφ/L ) 1 /2ETh-1 is negligible and the dominant contribution is provided by screening, G ˜(LT/L ) (Lφ/L ) 7 /2ETh-1 ; in this regime, the antisymmetric part is Ga˜(LT/L ) 2(Lφ/L ) 7 /2(gETh) -1 . All the precise dimensionless prefactors are obtained. Crossovers from zero to strong magnetic field regimes are also analyzed.

Coupling of active motion and advection shapes intracellular cargo transport.

PubMed

Khuc Trong, Philipp; Guck, Jochen; Goldstein, Raymond E

2012-07-13

Intracellular cargo transport can arise from passive diffusion, active motor-driven transport along cytoskeletal filament networks, and passive advection by fluid flows entrained by such cargo-motor motion. Active and advective transport are thus intrinsically coupled as related, yet different representations of the same underlying network structure. A reaction-advection-diffusion system is used here to show that this coupling affects the transport and localization of a passive tracer in a confined geometry. For sufficiently low diffusion, cargo localization to a target zone is optimized either by low reaction kinetics and decoupling of bound and unbound states, or by a mostly disordered cytoskeletal network with only weak directional bias. These generic results may help to rationalize subtle features of cytoskeletal networks, for example as observed for microtubules in fly oocytes.

Kikuchi-Fujimoto Disease Associated with Myasthenia Gravis: A Case Report

PubMed Central

Onasanya, Olukayode; Nochlin, David; Casas, Victor; Peddareddygari, Leema Reddy; Grewal, Raji P.

2010-01-01

Kikuchi-Fujimoto disease is a self-limited benign condition of unknown etiology characterized by cervical lymphadenopathy, fever, and leucopenia. An autoimmune hypothesis has been suggested and an association with systemic lupus erythematosus, Sjogren's disease, and antiphospholipid syndrome has been noted. We report a 27-year-old male who presented for evaluation of weakness and he was diagnosed with seropositive generalized myasthenia gravis and underwent a thymectomy. He was stable until five months post-thymectomy, when he developed a high fever associated with nontender cervical lymphadenopathy, chills, and night sweats. Histopathology of a cervical lymph gland biopsy was compatible with Kikuchi-Fujimoto lymphadenitis. He improved spontaneously and was asymptomatic at the followup six months later. Our case expands the association of Kikuchi-Fujimoto disease with autoimmune disorders to include myasthenia gravis. PMID:20814564

Space-time thermodynamics of the glass transition

NASA Astrophysics Data System (ADS)

Merolle, Mauro; Garrahan, Juan P.; Chandler, David

2005-08-01

We consider the probability distribution for fluctuations in dynamical action and similar quantities related to dynamic heterogeneity. We argue that the so-called “glass transition” is a manifestation of low action tails in these distributions where the entropy of trajectory space is subextensive in time. These low action tails are a consequence of dynamic heterogeneity and an indication of phase coexistence in trajectory space. The glass transition, where the system falls out of equilibrium, is then an order-disorder phenomenon in space-time occurring at a temperature Tg, which is a weak function of measurement time. We illustrate our perspective ideas with facilitated lattice models and note how these ideas apply more generally. Author contributions: M.M., J.P.G., and D.C. performed research and wrote the paper.

A New Closed Form Approximation for BER for Optical Wireless Systems in Weak Atmospheric Turbulence

NASA Astrophysics Data System (ADS)

Kaushik, Rahul; Khandelwal, Vineet; Jain, R. C.

2018-04-01

Weak atmospheric turbulence condition in an optical wireless communication (OWC) is captured by log-normal distribution. The analytical evaluation of average bit error rate (BER) of an OWC system under weak turbulence is intractable as it involves the statistical averaging of Gaussian Q-function over log-normal distribution. In this paper, a simple closed form approximation for BER of OWC system under weak turbulence is given. Computation of BER for various modulation schemes is carried out using proposed expression. The results obtained using proposed expression compare favorably with those obtained using Gauss-Hermite quadrature approximation and Monte Carlo Simulations.

Stress reactivity predicts symptom improvement in children with anxiety disorders.

PubMed

Dieleman, Gwendolyn C; Huizink, Anja C; Tulen, Joke H M; Utens, Elisabeth M W J; Tiemeier, Henning

2016-05-15

We examined the longitudinal associations of autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) axis rest and reactivity measures with anxiety and depressive symptoms at one-year follow-up in children with anxiety disorders. In a clinical sample of 152 children with a primary DSM-IV anxiety disorder, aged 8 to 12 years, anxiety and depressive symptoms were assessed with the Multidimensional Anxiety Scale for Children and the Children's Depression Inventory at pre-treatment baseline and one year later, after treatment with cognitive behavioral therapy. At baseline, children participated in a 70min stress task. Salivary cortisol was measured directly prior to and 20min post stress task. Skin conductance level (SCL), heart rate and high frequency heart rate variability (HRV) were continuously measured during rest and the stress task. To investigate if rest or reactivity measures predicted anxiety and depressive symptoms at one year follow-up, linear regression analyses were conducted for rest and reactivity measures of SCL, heart rate, HRV and cortisol separately. Higher SCL reactivity predicted less decrease of anxiety symptoms at one-year follow-up. Cortisol reactivity showed a weak association with depressive symptoms at one-year follow-up: lower cortisol reactivity predicted less decrease in depressive symptoms. Only self-reported anxiety and depressive symptoms were used. However, all predictors were objective biological measures, hence there is no risk of shared method variance bias. These findings suggest that pre-treatment HPA and ANS responsiveness to stress are predictive biomarkers for a lack of symptom improvement in children with a clinical anxiety disorder. Copyright © 2016 Elsevier B.V. All rights reserved.

Super-quantum correlation for SU(2) invariant state in 4⊗ 2 system

NASA Astrophysics Data System (ADS)

Li, Lin-Song; Tao, Yuan-Hong; Nan, Hua; Xu, Hui

2018-04-01

We analytically evaluate the weak one-way deficit and super-quantum discord for a system composed of spin-3/2 and spin-1/2 subsystems possessing SU(2) symmetry. We also make a comparative study of the relationships among the quantum discord, one-way deficit, weak one-way deficit, and super-quantum discord for the SU(2) invariant state. It is shown that super-quantum discord via weak measurement is greater than that via von Neumann measurement. But weak one-way deficit is less than the one-way deficit. As a result, weak measurement do not always reveal more quantumness.

Uniqueness of solutions for a mathematical model for magneto-viscoelastic flows

NASA Astrophysics Data System (ADS)

Schlömerkemper, A.; Žabenský, J.

2018-06-01

We investigate uniqueness of weak solutions for a system of partial differential equations capturing behavior of magnetoelastic materials. This system couples the Navier–Stokes equations with evolutionary equations for the deformation gradient and for the magnetization obtained from a special case of the micromagnetic energy. It turns out that the conditions on uniqueness coincide with those for the well-known Navier–Stokes equations in bounded domains: weak solutions are unique in two spatial dimensions, and weak solutions satisfying the Prodi–Serrin conditions are unique among all weak solutions in three dimensions. That is, we obtain the so-called weak-strong uniqueness result in three spatial dimensions.

Poverty and common mental disorders in developing countries.

PubMed Central

Patel, Vikram; Kleinman, Arthur

2003-01-01

A review of English-language journals published since 1990 and three global mental health reports identified 11 community studies on the association between poverty and common mental disorders in six low- and middle-income countries. Most studies showed an association between indicators of poverty and the risk of mental disorders, the most consistent association being with low levels of education. A review of articles exploring the mechanism of the relationship suggested weak evidence to support a specific association with income levels. Factors such as the experience of insecurity and hopelessness, rapid social change and the risks of violence and physical ill-health may explain the greater vulnerability of the poor to common mental disorders. The direct and indirect costs of mental ill-health worsen the economic condition, setting up a vicious cycle of poverty and mental disorder. Common mental disorders need to be placed alongside other diseases associated with poverty by policy-makers and donors. Programmes such as investment in education and provision of microcredit may have unanticipated benefits in reducing the risk of mental disorders. Secondary prevention must focus on strengthening the ability of primary care services to provide effective treatment. PMID:14576893

Molecular mechanisms underlying neurodevelopmental disorders, ADHD and autism.

PubMed

Bădescu, George Mihai; Fîlfan, Mădălina; Sandu, Raluca Elena; Surugiu, Roxana; Ciobanu, Ovidiu; Popa-Wagner, Aurel

2016-01-01

Neurodevelopmental disorders such as attention deficit hyperactivity disorder and autism represent a significant economic burden, which justify vigorous research to uncover its genetics and developmental clinics for a diagnostic workup. The urgency of addressing attention deficit hyperactivity disorder comorbidities is seen in the chilling fact that attention deficit hyperactivity disorder (ADHD), mood disorders, substance use disorders and obesity each increase the risk for mortality. However, data about comorbidity is mainly descriptive, with mechanistic studies limited to genetic epidemiological studies that document shared genetic risk factors among these conditions. Autism and intellectual disability affects 1.5 to 2% of the population in Western countries with many individuals displaying social-emotional agnosia and having difficulty in forming attachments and relationships. Underlying mechanisms include: (i) dysfunctions of neuronal miRNAs; (ii) deletions in the chromosome 21, subtelomeric deletions, duplications and a maternally inherited duplication of the chromosomal region 15q11-q13; (iii) microdeletions in on the long (q) arm of the chromosome in a region designated q21.1 increases the risk of delayed development, intellectual disability, physical abnormalities, and neurological and psychiatric problems associated with autism, schizophrenia, and epilepsy and weak muscle tone (hypotonia); (iv) interstitial duplications encompassing 16p13.11.

Conversion disorder: current problems and potential solutions for DSM-5.

PubMed

Stone, Jon; LaFrance, W Curt; Brown, Richard; Spiegel, David; Levenson, James L; Sharpe, Michael

2011-12-01

Conversion disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) describes neurological symptoms, including weakness, numbness and events resembling epilepsy or syncope, which can be positively identified as not being due to recognised neurological disease. This review combines perspectives from psychiatry, psychology and neurology to identify and discuss key problems with the current diagnostic DSM-IV criteria for conversion disorder and to make the following proposals for DSM-5: (a) abandoning the label "conversion disorder" and replacing it with an alternative term that is both theoretically neutral and potentially more acceptable to patients and practitioners; (b) relegating the requirements for "association of psychological factors" and the "exclusion of feigning" to the accompanying text; (c) adding a criterion requiring clinical findings of internal inconsistency or incongruity with recognised neurological or medical disease and altering the current 'disease exclusion' criteria to one in which the symptom must not be 'better explained' by a disease if present, (d) adding a 'cognitive symptoms' subtype. We also discuss whether conversion symptoms are better classified with other somatic symptom disorders or with dissociative disorders and how we might address the potential heterogeneity of conversion symptoms in classification. 2011 Elsevier Inc. All rights reserved.

Poverty and common mental disorders in developing countries.

PubMed

Patel, Vikram; Kleinman, Arthur

2003-01-01

A review of English-language journals published since 1990 and three global mental health reports identified 11 community studies on the association between poverty and common mental disorders in six low- and middle-income countries. Most studies showed an association between indicators of poverty and the risk of mental disorders, the most consistent association being with low levels of education. A review of articles exploring the mechanism of the relationship suggested weak evidence to support a specific association with income levels. Factors such as the experience of insecurity and hopelessness, rapid social change and the risks of violence and physical ill-health may explain the greater vulnerability of the poor to common mental disorders. The direct and indirect costs of mental ill-health worsen the economic condition, setting up a vicious cycle of poverty and mental disorder. Common mental disorders need to be placed alongside other diseases associated with poverty by policy-makers and donors. Programmes such as investment in education and provision of microcredit may have unanticipated benefits in reducing the risk of mental disorders. Secondary prevention must focus on strengthening the ability of primary care services to provide effective treatment.

Vitamin D Status at Birth and Future Risk of Attention Deficit/Hyperactivity Disorder (ADHD).

PubMed

Gustafsson, Peik; Rylander, Lars; Lindh, Christian H; Jönsson, Bo A G; Ode, Amanda; Olofsson, Per; Ivarsson, Sten A; Rignell-Hydbom, Anna; Haglund, Nils; Källén, Karin

2015-01-01

To investigate whether children with Attention Deficit/Hyperactivity Disorder have lower levels of Vitamin D3 at birth than matched controls. Umbilical cord blood samples collected at birth from 202 children later diagnosed with Attention Deficit/Hyperactivity Disorder were analysed for vitamin D content and compared with 202 matched controls. 25-OH vitamin D3 was analysed by liquid chromatography tandem mass spectrometry. No differences in cord blood vitamin D concentration were found between children with Attention Deficit/Hyperactivity Disorder (median 13.0 ng/ml) and controls (median 13.5 ng/ml) (p = 0.43). In a logistic regression analysis, Attention Deficit/Hyperactivity Disorder showed a significant association with maternal age (odds ratio: 0.96, 95% confidence interval: 0.92-0.99) but not with vitamin D levels (odds ratio: 0.99, 95% confidence interval: 0.97-1.02). We found no difference in intrauterine vitamin D levels between children later developing Attention Deficit/Hyperactivity Disorder and matched control children. However, the statistical power of the study was too weak to detect an eventual small to medium size association between vitamin D levels and Attention Deficit/Hyperactivity Disorder.

$$\\chi$$EFT studies of few-nucleon systems: a status report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiavilla, Rocco

2016-06-01

A status report onmore » $$\\chi$$EFT studies of few-nucleon electroweak structure and dynamics is provided, including electromagnetic elastic form factors of few-nucleon systems, the $pp$ weak fusion and muon weak captures on deuteron and $^3$He, and a number of parity-violating processes induced by hadronic weak interactions.« less

Septic Arthritis

MedlinePlus

... Weak immune system. People with a weak immune system are at greater risk of septic arthritis. This includes people with diabetes, kidney and liver problems, and those taking drugs that suppress their immune systems. Joint trauma. Animal bites, puncture woods or cuts ...

Non-conventional synchronization of weakly coupled active oscillators

NASA Astrophysics Data System (ADS)

Manevitch, L. I.; Kovaleva, M. A.; Pilipchuk, V. N.

2013-03-01

We present a new type of self-sustained vibrations in the fundamental physical model covering a broad area of applications from wave generation in radiophysics and nonlinear optics to the heart muscle contraction and eyesight disorder in biophysics. Such a diversity of applications is due to the universal physical phenomenon of synchronization. Previous studies of this phenomenon, originating from Huygens famous observation, are based mainly on the model of two weakly coupled Van der Pol oscillators and usually deal with their synchronization in the regimes close to nonlinear normal modes (NNMs). In this work, we show for the first time that, in the important case of threshold excitation, an alternative synchronization mechanism can develop when the conventional synchronization becomes impossible. We identify this mechanism as an appearance of dynamic attractor with the complete periodic energy exchange between the oscillators, which is the dissipative analogue of highly intensive beats in a conservative system. This type of motion is therefore opposite to the NNM-type synchronization with no energy exchange by definition. The analytical description of these vibrations employs the concept of Limiting Phase Trajectories (LPTs) introduced by one of the authors earlier for conservative systems. Finally, within the LPT approach, we describe the transition from the complete energy exchange between the oscillators to the energy localization mostly on one of the two oscillators. The localized mode is an attractor in the range of model parameters wherein the LPT as well as the in-phase and out-of-phase NNMs become unstable.

Associations between DSM-IV mental disorders and subsequent COPD diagnosis.

PubMed

Rapsey, Charlene M; Lim, Carmen C W; Al-Hamzawi, Ali; Alonso, Jordi; Bruffaerts, Ronny; Caldas-de-Almeida, J M; Florescu, Silvia; de Girolamo, Giovanni; Hu, Chiyi; Kessler, Ronald C; Kovess-Masfety, Viviane; Levinson, Daphna; Medina-Mora, María Elena; Murphy, Sam; Ono, Yutaka; Piazza, Maria; Posada-Villa, Jose; ten Have, Margreet; Wojtyniak, Bogdan; Scott, Kate M

2015-11-01

COPD and mental disorder comorbidity is commonly reported, although findings are limited by substantive weaknesses. Moreover, few studies investigate mental disorder as a risk for COPD onset. This research aims to investigate associations between current (12-month) DSM-IV mental disorders and COPD, associations between temporally prior mental disorders and subsequent COPD diagnosis, and cumulative effect of multiple mental disorders. Data were collected using population surveys of 19 countries (n=52,095). COPD diagnosis was assessed by self-report of physician's diagnosis. The World Mental Health-Composite International Diagnostic Interview (WMH-CIDI) was used to retrospectively assess lifetime prevalence and age at onset of 16 DSM-IV disorders. Adjusting for age, gender, smoking, education, and country, survival analysis estimated associations between first onset of mental disorder and subsequent COPD diagnosis. COPD and several mental disorders were concurrently associated across the 12-month period (ORs 1.5-3.8). When examining associations between temporally prior disorders and COPD, all but two mental disorders were associated with COPD diagnosis (ORs 1.7-3.5). After comorbidity adjustment, depression, generalized anxiety disorder, and alcohol abuse were significantly associated with COPD (ORs 1.6-1.8). There was a substantive cumulative risk of COPD diagnosis following multiple mental disorders experienced over the lifetime. Mental disorder prevalence is higher in those with COPD than those without COPD. Over time, mental disorders are associated with subsequent diagnosis of COPD; further, the risk is cumulative for multiple diagnoses. Attention should be given to the role of mental disorders in the pathogenesis of COPD using prospective study designs. Copyright © 2015 Elsevier Inc. All rights reserved.

Associations between DSM-IV mental disorders and subsequent COPD diagnosis

PubMed Central

Rapsey, Charlene M.; Lim, Carmen C.W.; Al-Hamzawi, Ali; Alonso, Jordi; Bruffaerts, Ronny; Caldas-de-Almeida, J.M.; Florescu, Silvia; de Girolamo, Giovanni; Hu, Chiyi; Kessler, Ronald C.; Kovess-Masfety, Viviane; Levinson, Daphna; Elena Medina-Mora, María; Murphy, Sam; Ono, Yutaka; Piazza, Maria; Posada-Villa, Jose; ten Have, Margreet; Wojtyniak, Bogdan; Scott, Kate M.

2016-01-01

Objectives COPD and mental disorder comorbidity is commonly reported, although findings are limited by substantive weaknesses. Moreover, few studies investigate mental disorder as a risk for COPD onset. This research aims to investigate associations between current (12-month) DSM-IV mental disorders and COPD, associations between temporally prior mental disorders and subsequent COPD diagnosis, and cumulative effect of multiple mental disorders. Methods Data were collected using population surveys of 19 countries (n = 52,095). COPD diagnosis was assessed by self-report of physician's diagnosis. The World Mental Health-Composite International Diagnostic Interview (WMH-CIDI) was used to retrospectively assess lifetime prevalence and age at onset of 16 DSM-IV disorders. Adjusting for age, gender, smoking, education, and country, survival analysis estimated associations between first onset of mental disorder and subsequent COPD diagnosis. Results COPD and several mental disorders were concurrently associated across the 12-month period (ORs 1.5–3.8). When examining associations between temporally prior disorders and COPD, all but two mental disorders were associated with COPD diagnosis (ORs 1.7–3.5). After comorbidity adjustment, depression, generalized anxiety disorder, and alcohol abuse were significantly associated with COPD (ORs 1.6–1.8). There was a substantive cumulative risk of COPD diagnosis following multiple mental disorders experienced over the lifetime. Conclusions: Mental disorder prevalence is higher in those with COPD than those without COPD. Over time, mental disorders are associated with subsequent diagnosis of COPD; further, the risk is cumulative for multiple diagnoses. Attention should be given to the role of mental disorders in the pathogenesis of COPD using prospective study designs. PMID:26526305

Polariton condensation in a strain-compensated planar microcavity with InGaAs quantum wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cilibrizzi, Pasquale; Askitopoulos, Alexis, E-mail: Alexis.Askitopoulos@soton.ac.uk; Silva, Matteo

2014-11-10

The investigation of intrinsic interactions in polariton condensates is currently limited by the photonic disorder of semiconductor microcavity structures. Here, we use a strain compensated planar GaAs/AlAs{sub 0.98}P{sub 0.02} microcavity with embedded InGaAs quantum wells having a reduced cross-hatch disorder to overcome this issue. Using real and reciprocal space spectroscopic imaging under non-resonant optical excitation, we observe polariton condensation and a second threshold marking the onset of photon lasing, i.e., the transition from the strong to the weak-coupling regime. Condensation in a structure with suppressed photonic disorder is a necessary step towards the implementation of periodic lattices of interacting condensates,more » providing a platform for on chip quantum simulations.« less

Random electric field instabilities of relaxor ferroelectrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arce-Gamboa, Jose R.; Guzman-Verri, Gian G.

Relaxor ferroelectrics are complex oxide materials which are rather unique to study the effects of compositional disorder on phase transitions. Here, we study the effects of quenched cubic random electric fields on the lattice instabilities that lead to a ferroelectric transition and show that, within a microscopic model and a statistical mechanical solution, even weak compositional disorder can prohibit the development of long-range order and that a random field state with anisotropic and power-law correlations of polarization emerges from the combined effect of their characteristic dipole forces and their inherent charge disorder. As a result, we compare and reproduce severalmore » key experimental observations in the well-studied relaxor PbMg 1/3Nb 2/3O 3–PbTiO 3.« less

Patient-reported outcomes in borderline personality disorder.

PubMed

Hasler, Gregor; Hopwood, Christopher J; Jacob, Gitta A; Brändle, Laura S; Schulte-Vels, Thomas

2014-06-01

Patient-reported outcome (PRO) refers to measures that emphasize the subjective view of patients about their health-related conditions and behaviors. Typically, PROs include self-report questionnaires and clinical interviews. Defining PROs for borderline personality disorder (BPD) is particularly challenging given the disorder's high symptomatic heterogeneity, high comorbidity with other psychiatric conditions, highly fluctuating symptoms, weak correlations between symptoms and functional outcomes, and lack of valid and reliable experimental measures to complement self-report data. Here, we provide an overview of currently used BPD outcome measures and discuss them from clinical, psychometric, experimental, and patient perspectives. In addition, we review the most promising leads to improve BPD PROs, including the DSM-5 Section III, the Recovery Approach, Ecological Momentary Assessments, and novel experimental measures of social functioning that are associated with functional and social outcomes.

Myasthenia Gravis: A Review

PubMed Central

Jayam Trouth, Annapurni; Dabi, Alok; Solieman, Noha; Kurukumbi, Mohankumar; Kalyanam, Janaki

2012-01-01

Acquired myasthenia gravis is a relatively uncommon disorder, with prevalence rates that have increased to about 20 per 100,000 in the US population. This autoimmune disease is characterized by muscle weakness that fluctuates, worsening with exertion, and improving with rest. In about two-thirds of the patients, the involvement of extrinsic ocular muscle presents as the initial symptom, usually progressing to involve other bulbar muscles and limb musculature, resulting in generalized myasthenia gravis. Although the cause of the disorder is unknown, the role of circulating antibodies directed against the nicotinic acetylcholine receptor in its pathogenesis is well established. As this disorder is highly treatable, prompt recognition is crucial. During the past decade, significant progress has been made in our understanding of the disease, leading to new treatment modalities and a significant reduction in morbidity and mortality. PMID:23193443

Quantum-state transfer through long-range correlated disordered channels

NASA Astrophysics Data System (ADS)

Almeida, Guilherme M. A.; de Moura, Francisco A. B. F.; Lyra, Marcelo L.

2018-05-01

We study quantum-state transfer in XX spin-1/2 chains where both communicating spins are weakly coupled to a channel featuring disordered on-site magnetic fields. Fluctuations are modeled by long-range correlated sequences with self-similar profile obeying a power-law spectrum. We show that the channel is able to perform almost perfect quantum-state transmissions even in the presence of significant amounts of disorder provided the degree of those correlations is strong enough, with the cost of having long transfer times and unavoidable timing errors. Still, we show that the lack of mirror symmetry in the channel does not affect much the likelihood of having high-quality outcomes. Our results suggest that coexistence between localized and delocalized states can diminish effects of static perturbations in solid-state devices for quantum communication.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jana, R. N.; Meikap, A. K.

The results of a comprehensive study of weak electron localization (WEL) and electron-electron interaction (EEI) effects in disordered V{sub 75}X{sub 25} (X = Pd, Al) alloys has been reported. The resistivity in absence of magnetic field shows a minimum at temperature T = T{sub m} and follows T{sup 1/2} law within the temperature range 5 K ≤ T ≤ T{sub m}, which suggests predominant EEI effect. Magnetoresistivity is positive due to strong spin-orbit interaction. The dephasing scattering time is dominated by the electron-phonon scattering. The electron-phonon scattering rate shows quadratic temperature dependence behavior, which is explained by the theory ofmore » incomplete dragging at the random scattering potential by phonons. The zero temperature scattering time strongly depends on the disorder and its magnitude decreases with increasing disorder.« less

Random electric field instabilities of relaxor ferroelectrics

DOE PAGES

Arce-Gamboa, Jose R.; Guzman-Verri, Gian G.

2017-06-13

Relaxor ferroelectrics are complex oxide materials which are rather unique to study the effects of compositional disorder on phase transitions. Here, we study the effects of quenched cubic random electric fields on the lattice instabilities that lead to a ferroelectric transition and show that, within a microscopic model and a statistical mechanical solution, even weak compositional disorder can prohibit the development of long-range order and that a random field state with anisotropic and power-law correlations of polarization emerges from the combined effect of their characteristic dipole forces and their inherent charge disorder. As a result, we compare and reproduce severalmore » key experimental observations in the well-studied relaxor PbMg 1/3Nb 2/3O 3–PbTiO 3.« less

[An update on myasthenia gravis].

PubMed

Martínez Torre, S; Gómez Molinero, I; Martínez Girón, R

2018-03-16

Myasthenia gravis is one of the most common disorders that affect neuromuscular transmission. It is currently one of the most understood and characterised autoimmune disorders Its typical symptoms are fluctuating weakness and fatigue that affects a combination of ocular muscles, bulbar functions, as well as limb and respiratory muscles, which are due to an immune attack against the postsynaptic membrane of the neuromuscular junction. The diagnosis of myasthenia gravis is based on clinical and serological test. It is a disease that can be effectively controlled with the current therapeutic lines, even achieving a complete remission. An update of this interesting disorder is now presented. Copyright © 2018 Sociedad Española de Médicos de Atención Primaria (SEMERGEN). Publicado por Elsevier España, S.L.U. All rights reserved.

Day-night contrast as source of health for the human circadian system.

PubMed

Martinez-Nicolas, Antonio; Madrid, Juan Antonio; Rol, Maria Angeles

2014-04-01

Modern societies are characterized by a 24/7 lifestyle (LS) with no environmental differences between day and night, resulting in weak zeitgebers (weak day light, absence of darkness during night, constant environmental temperature, sedentary LS and frequent snacking), and as a consequence, in an impaired circadian system (CS) through a process known as chronodisruption. Both weak zeitgebers and CS impairment are related to human pathologies (certain cancers, metabolic syndrome and affective and cognitive disorders), but little is known about how to chronoenhance the CS. The aim of this work is to propose practical strategies for chronoenhancement, based on accentuating the day/night contrast. For this, 131 young subjects were recruited, and their wrist temperature (WT), activity, body position, light exposure, environmental temperature and sleep were recorded under free-living conditions for 1 week. Subjects with high contrast (HC) and low contrast (LC) for each variable were selected to analyze the HC effect in activity, body position, environmental temperature, light exposure and sleep would have on WT. We found that HC showed better rhythms than LC for every variable except sleep. Subjects with HC and LC for WT also demonstrated differences in LS, where HC subjects had a slightly advanced night phase onset and a general increase in day/night contrast. In addition, theoretical high day/night contrast calculated using mathematical models suggests an improvement by means of LS contrast. Finally, some individuals classified as belonging to the HC group in terms of WT when they are exposed to the LS characteristic of the LC group, while others exhibit WT arrhythmicity despite their good LS habits, revealing two different WT components: an exogenous component modified by LS and another endogenous component that is refractory to it. Therefore, intensifying day/night contrast in subject's LS has proven to be a feasible measure to chronoenhance the CS.

Probing equilibrium by nonequilibrium dynamics: Aging in Co/Cr superlattices

NASA Astrophysics Data System (ADS)

Binek, Christian

2013-03-01

Magnetic aging phenomena are investigated in a structurally ordered Co/Cr superlattice through measurements of magnetization relaxation, magnetic susceptibility, and hysteresis at various temperatures above and below the onset of collective magnetic order. We take advantage of the fact that controlled growth of magnetic multilayer thin films via molecular beam epitaxy allows tailoring the intra and inter-layer exchange interaction and thus enables tuning of magnetic properties including the spin-fluctuation spectra. Tailored nanoscale periodicity in Co/Cr multilayers creates mesoscopic spatial magnetic correlations with slow relaxation dynamics when quenching the system into a nonequilibrium state. Magnetization relaxation in weakly correlated spin systems depends on the microscopic spin-flip time of about 10 ns and is therefore a fast process. The spin correlations in our Co/Cr superlattice bring the magnetization dynamics to experimentally better accessible time scales of seconds or hours. In contrast to spin-glasses, where slow dynamics due to disorder and frustration is a well-known phenomenon, we tune and increase relaxation times in ordered structures. This is achieved by increasing spin-spin correlation between mesoscopically correlated regions rather than individual atomic spins, a concept with some similarity to block spin renormalization. Magnetization transients are measured after exposing the Co/Cr heterostructure to a magnetic set field for various waiting times. Scaling analysis reveals an asymptotic power-law behavior in accordance with a full aging scenario. The temperature dependence of the relaxation exponent shows pronounced anomalies at the equilibrium phase transitions of the antiferromagnetic superstructure and the ferromagnetic to paramagnetic transition of the Co layers. The latter leaves only weak fingerprints in the equilibrium magnetic behavior but gives rise to a prominent change in nonequilibrium properties. Our findings suggest that scaling analysis of nonequilibrium data can serve as a probe for weak equilibrium phase transitions. Financial support by NRI, and NSF through EPSCoR, and MRSEC 0820521 is greatly acknowledged.

Classification and characterization of topological insulators and superconductors

NASA Astrophysics Data System (ADS)

Mong, Roger

Topological insulators (TIs) are a new class of materials which, until recently, have been overlooked despite decades of study in band insulators. Like semiconductors and ordinary insulators, TIs have a bulk gap, but feature robust surfaces excitations which are protected from disorder and interactions which do not close the bulk gap. TIs are distinguished from ordinary insulators not by the symmetries they possess (or break), but by topological invariants characterizing their bulk band structures. These two pictures, the existence of gapless surface modes, and the nontrivial topology of the bulk states, yield two contrasting approaches to the study of TIs. At the heart of the subject, they are connected by the bulk-boundary correspondence, relating bulk and surface degrees of freedom. In this work, we study both aspects of topological insulators, at the same time providing an illumination to their mysterious connection. First, we present a systematic approach to the classification of bulk states of systems with inversion-like symmetries, deriving a complete set of topological invariants for such ensembles. We find that the topological invariants in all dimensions may be computed algebraically via exact sequences. In particular, systems with spatial inversion symmetries in one-, two-, and three-dimensions can be classified by, respectively, 2, 5, and 11 integer invariants. The values of these integers are related to physical observables such as polarization, Hall conductivity, and magnetoelectric coupling. We also find that, for systems with “antiferromagnetic symmetry,” there is a Z2 classification in three-dimensions, and hence a class of “antiferromagnetic topological insulators” (AFTIs) which are distinguished from ordinary antiferromagnets. From the perspective of the bulk, AFTI exhibits the quantized magnetoelectric effect, whereas on the surface, gapless one-dimensional chiral modes emerge at step-defects. Next, we study how the surface spectrum can be computed from bulk quantities. Specifically, we present an analytic prescription for computing the edge dispersion E(k) of a tight-binding Dirac Hamiltonian terminated at an abrupt crystalline edge, based on the bulk Hamiltonian. The result is presented as a geometric formula, relating the existence of surface states as well as their energy dispersion to properties of the bulk Hamiltonian. We further prove the bulk-boundary correspondence for this specific class of systems, connecting the Chern number and the chiral edge modes for quantum Hall systems given in terms of Dirac Hamiltonians. In similar spirit, we examine the existence of Majorana zero modes in superconducting doped-TIs. We find that Majorana zero modes indeed appear but only if the doped Fermi energy is below a critical chemical potential. The critical doping is associated with a topological phase transition of vortex lines, which supports gapless excitations spanning their length. For weak pairing, the critical point is dependent on the non-abelian Berry phase of the bulk Fermi surface. Finally, we investigate the transport properties on the surfaces of TIs. While the surfaces of “strong topological insulators” - TIs with an odd number of Dirac cones in their surface spectrum - have been well studied in literature, studies of their counterpart “weak topological insulators” (WTIs) are meager, with conflicting claims. Because WTIs have an even number of Dirac cones in their surface spectrum, they are thought to be unstable to disorder, which leads to an insulating surface. Here we argue that the presence of disorder alone will not localize the surface states, rather, presence of a time-reversal symmetric mass term is required for localization. Through numerical simulations, we show that in the absence of the mass term the surface always flow to a stable metallic phase and the conductivity obeys a one-parameter scaling relation, just as in the case of a strong topological insulator surface. With the inclusion of the mass, the transport properties of the surface of a weak topological insulator follow a two-parameter scaling form, reminiscent of the quantum Hall phase transition.

Hypokalemic Periodic Paralysis: a case report and review of the literature

PubMed Central

Soule, Benjamin R; Simone, Nicole L

2008-01-01

Hypokalemic Periodic Paralysis is one form of Periodic Paralysis, a rare group of disorders that can cause of sudden onset weakness. A case of a 29 year old male is presented here. The patient presented with sudden onset paralysis of his extremities. Laboratory evaluation revealed a markedly low potassium level. The patient's paralysis resolved upon repletion of his low potassium and he was discharged with no neurologic deficits. An association with thyroid disease is well established and further workup revealed Grave's disease in this patient. Although rare, Periodic Paralysis must differentiated from other causes of weakness and paralysis so that the proper treatment can be initiated quickly. PMID:18939979

[Methods of brain stimulation based on weak electric current--future tool for the clinician?].

PubMed

Kotilainen, Tuukka; Lehto, Soili M

2016-01-01

Methods of brain stimulation based on a weak electric current are non-invasive neuromodulation techniques. They include transcranial direct current, alternating current and random noise stimulation. These methods modify the membrane potential of neurons without triggering the action potential, and have been successfully utilized to influence cognition and regulation of emotions in healthy experimental subjects. In clinical studies, indications of the efficacy of these techniques have been obtained in the treatment of depression, schizophrenia, memory disorders and pain as well as in stroke rehabilitation. It is hoped that these techniques will become established as part of the care and rehabilitation of psychiatric and neurologic patients in the future.

Food matters: how the microbiome and gut-brain interaction might impact the development and course of anorexia nervosa.

PubMed

Herpertz-Dahlmann, Beate; Seitz, Jochen; Baines, John

2017-09-01

Anorexia nervosa (AN) is one of the most common chronic illnesses in female adolescents and exhibits the highest mortality risk of all psychiatric disorders. Evidence for the effectiveness of psychotherapeutic or psychopharmacological interventions is weak. Mounting data indicate that the gut microbiome interacts with the central nervous system and the immune system by neuroendocrine, neurotransmitter, neurotrophic and neuroinflammatory afferent and efferent pathways. There is growing evidence that the gut microbiota influences weight regulation and psychopathology, such as anxiety and depression. This article reviews how the gut-brain interaction may impact the development and course of AN. A "leaky gut", characterized by antigens traversing the intestinal wall, was demonstrated in an animal model of AN, and could underlie the low-grade inflammation and increased risk of autoimmune diseases found in AN. Moreover, starvation has a substantial impact on the gut microbiome, and diets used for re-nutrition based on animal products may support the growth of bacteria capable of triggering inflammation. As there is currently no empirically derived agreement on therapeutic re-nourishment in AN, this review discusses how consideration of gut-brain interactions may be important for treatment regarding the determination of target weight, rapidity of weight gain, refeeding methods and composition of the diet which might all be of importance to improve long-term outcome of one of the most chronic psychiatric disorders of adolescence.

Visceral leishmaniasis in a patient with systemic lupus erythematosus.

PubMed

Santos Silva, André Filipe; Figueiredo Dias, João Paulo Branco Calheiros; Nuak, João Miguel Neves Gonçalves Santos; Rocha Aguiar, Francisca; Araújo Pinto, José António; Sarmento, António Carlos Eugénio Megre

2015-01-01

Visceral leishmaniasis is an infection with an insidious and disabling course caused by parasites of the genus Leishmania. In Europe, it is mostly associated with HIV infection. Systemic lupus erythematosus and its treatment are associated with increased risk of infection, neoplastic and concomitant autoimmune disorders. The association of these diseases may go unnoticed. A 60 year-old Caucasian woman with lupus presented with a one-year history of fever, malaise, weakness and weight loss. The highlights on physical examination were pallor, palpable hepatosplenomegaly and low-grade fever. Blood tests showed pancytopenia, hyperproteinemia with hypoalbuminemia and hypergammaglobulinemia; electrophoresis showed a polyclonal gamma curve. Full-body CT scan revealed massive hepatosplenomegaly. Microbiology investigation was negative for the most common pathogens, including tuberculosis. There were no signs of hematologic malignancy in the bone marrow smear. PCR for Leishmania infantum was positive both in blood and bone marrow. The patient was treated with liposomal amphotericin B, and immunosuppression was adjusted. She showed rapid clinical improvement and 6 months later had no signs of disease. The differential diagnosis in a patient with lupus presenting with fever and multisystemic manifestations includes infectious or neoplastic disorders. The patient lived in an endemic area of Leishmania, and typical clinical and analytical changes were all present, making this case highly educational. The case highlights the importance of a patient's epidemiological background and how it can lead to the diagnosis and timely treatment of a rare disease.

Loss-of-function mutations in SCN4A cause severe foetal hypokinesia or ‘classical’ congenital myopathy

PubMed Central

Zaharieva, Irina T.; Thor, Michael G.; Oates, Emily C.; van Karnebeek, Clara; Hendson, Glenda; Blom, Eveline; Witting, Nanna; Rasmussen, Magnhild; Gabbett, Michael T.; Ravenscroft, Gianina; Sframeli, Maria; Suetterlin, Karen; Sarkozy, Anna; D’Argenzio, Luigi; Hartley, Louise; Matthews, Emma; Pitt, Matthew; Vissing, John; Ballegaard, Martin; Krarup, Christian; Slørdahl, Andreas; Halvorsen, Hanne; Ye, Xin Cynthia; Zhang, Lin-Hua; Løkken, Nicoline; Werlauff, Ulla; Abdelsayed, Mena; Davis, Mark R.; Feng, Lucy; Phadke, Rahul; Sewry, Caroline A.; Morgan, Jennifer E.; Laing, Nigel G.; Vallance, Hilary; Ruben, Peter; Hanna, Michael G.; Lewis, Suzanne; Kamsteeg, Erik-Jan; Männikkö, Roope

2016-01-01

Abstract See Cannon (doi: 10.1093/brain/awv400 ) for a scientific commentary on this article. Congenital myopathies are a clinically and genetically heterogeneous group of muscle disorders characterized by congenital or early-onset hypotonia and muscle weakness, and specific pathological features on muscle biopsy. The phenotype ranges from foetal akinesia resulting in in utero or neonatal mortality, to milder disorders that are not life-limiting. Over the past decade, more than 20 new congenital myopathy genes have been identified. Most encode proteins involved in muscle contraction; however, mutations in ion channel-encoding genes are increasingly being recognized as a cause of this group of disorders. SCN4A encodes the α-subunit of the skeletal muscle voltage-gated sodium channel (Na v 1.4). This channel is essential for the generation and propagation of the muscle action potential crucial to muscle contraction. Dominant SCN4A gain-of-function mutations are a well-established cause of myotonia and periodic paralysis. Using whole exome sequencing, we identified homozygous or compound heterozygous SCN4A mutations in a cohort of 11 individuals from six unrelated kindreds with congenital myopathy. Affected members developed in utero - or neonatal-onset muscle weakness of variable severity. In seven cases, severe muscle weakness resulted in death during the third trimester or shortly after birth. The remaining four cases had marked congenital or neonatal-onset hypotonia and weakness associated with mild-to-moderate facial and neck weakness, significant neonatal-onset respiratory and swallowing difficulties and childhood-onset spinal deformities. All four surviving cohort members experienced clinical improvement in the first decade of life. Muscle biopsies showed myopathic features including fibre size variability, presence of fibrofatty tissue of varying severity, without specific structural abnormalities. Electrophysiology suggested a myopathic process, without myotonia. In vitro functional assessment in HEK293 cells of the impact of the identified SCN4A mutations showed loss-of-function of the mutant Na v 1.4 channels. All, apart from one, of the mutations either caused fully non-functional channels, or resulted in a reduced channel activity. Each of the affected cases carried at least one full loss-of-function mutation. In five out of six families, a second loss-of-function mutation was present on the trans allele. These functional results provide convincing evidence for the pathogenicity of the identified mutations and suggest that different degrees of loss-of-function in mutant Na v 1.4 channels are associated with attenuation of the skeletal muscle action potential amplitude to a level insufficient to support normal muscle function. The results demonstrate that recessive loss-of-function SCN4A mutations should be considered in patients with a congenital myopathy. PMID:26700687

Loss-of-function mutations in SCN4A cause severe foetal hypokinesia or 'classical' congenital myopathy.

PubMed

Zaharieva, Irina T; Thor, Michael G; Oates, Emily C; van Karnebeek, Clara; Hendson, Glenda; Blom, Eveline; Witting, Nanna; Rasmussen, Magnhild; Gabbett, Michael T; Ravenscroft, Gianina; Sframeli, Maria; Suetterlin, Karen; Sarkozy, Anna; D'Argenzio, Luigi; Hartley, Louise; Matthews, Emma; Pitt, Matthew; Vissing, John; Ballegaard, Martin; Krarup, Christian; Slørdahl, Andreas; Halvorsen, Hanne; Ye, Xin Cynthia; Zhang, Lin-Hua; Løkken, Nicoline; Werlauff, Ulla; Abdelsayed, Mena; Davis, Mark R; Feng, Lucy; Phadke, Rahul; Sewry, Caroline A; Morgan, Jennifer E; Laing, Nigel G; Vallance, Hilary; Ruben, Peter; Hanna, Michael G; Lewis, Suzanne; Kamsteeg, Erik-Jan; Männikkö, Roope; Muntoni, Francesco

2016-03-01

Congenital myopathies are a clinically and genetically heterogeneous group of muscle disorders characterized by congenital or early-onset hypotonia and muscle weakness, and specific pathological features on muscle biopsy. The phenotype ranges from foetal akinesia resulting in in utero or neonatal mortality, to milder disorders that are not life-limiting. Over the past decade, more than 20 new congenital myopathy genes have been identified. Most encode proteins involved in muscle contraction; however, mutations in ion channel-encoding genes are increasingly being recognized as a cause of this group of disorders. SCN4A encodes the α-subunit of the skeletal muscle voltage-gated sodium channel (Nav1.4). This channel is essential for the generation and propagation of the muscle action potential crucial to muscle contraction. Dominant SCN4A gain-of-function mutations are a well-established cause of myotonia and periodic paralysis. Using whole exome sequencing, we identified homozygous or compound heterozygous SCN4A mutations in a cohort of 11 individuals from six unrelated kindreds with congenital myopathy. Affected members developed in utero- or neonatal-onset muscle weakness of variable severity. In seven cases, severe muscle weakness resulted in death during the third trimester or shortly after birth. The remaining four cases had marked congenital or neonatal-onset hypotonia and weakness associated with mild-to-moderate facial and neck weakness, significant neonatal-onset respiratory and swallowing difficulties and childhood-onset spinal deformities. All four surviving cohort members experienced clinical improvement in the first decade of life. Muscle biopsies showed myopathic features including fibre size variability, presence of fibrofatty tissue of varying severity, without specific structural abnormalities. Electrophysiology suggested a myopathic process, without myotonia. In vitro functional assessment in HEK293 cells of the impact of the identified SCN4A mutations showed loss-of-function of the mutant Nav1.4 channels. All, apart from one, of the mutations either caused fully non-functional channels, or resulted in a reduced channel activity. Each of the affected cases carried at least one full loss-of-function mutation. In five out of six families, a second loss-of-function mutation was present on the trans allele. These functional results provide convincing evidence for the pathogenicity of the identified mutations and suggest that different degrees of loss-of-function in mutant Nav1.4 channels are associated with attenuation of the skeletal muscle action potential amplitude to a level insufficient to support normal muscle function. The results demonstrate that recessive loss-of-function SCN4A mutations should be considered in patients with a congenital myopathy. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.

Congenital myasthenic syndromes due to mutations in ALG2 and ALG14.

PubMed

Cossins, Judith; Belaya, Katsiaryna; Hicks, Debbie; Salih, Mustafa A; Finlayson, Sarah; Carboni, Nicola; Liu, Wei Wei; Maxwell, Susan; Zoltowska, Katarzyna; Farsani, Golara Torabi; Laval, Steven; Seidhamed, Mohammed Zain; Donnelly, Peter; Bentley, David; McGowan, Simon J; Müller, Juliane; Palace, Jacqueline; Lochmüller, Hanns; Beeson, David

2013-03-01

Congenital myasthenic syndromes are a heterogeneous group of inherited disorders that arise from impaired signal transmission at the neuromuscular synapse. They are characterized by fatigable muscle weakness. We performed linkage analysis, whole-exome and whole-genome sequencing to determine the underlying defect in patients with an inherited limb-girdle pattern of myasthenic weakness. We identify ALG14 and ALG2 as novel genes in which mutations cause a congenital myasthenic syndrome. Through analogy with yeast, ALG14 is thought to form a multiglycosyltransferase complex with ALG13 and DPAGT1 that catalyses the first two committed steps of asparagine-linked protein glycosylation. We show that ALG14 is concentrated at the muscle motor endplates and small interfering RNA silencing of ALG14 results in reduced cell-surface expression of muscle acetylcholine receptor expressed in human embryonic kidney 293 cells. ALG2 is an alpha-1,3-mannosyltransferase that also catalyses early steps in the asparagine-linked glycosylation pathway. Mutations were identified in two kinships, with mutation ALG2p.Val68Gly found to severely reduce ALG2 expression both in patient muscle, and in cell cultures. Identification of DPAGT1, ALG14 and ALG2 mutations as a cause of congenital myasthenic syndrome underscores the importance of asparagine-linked protein glycosylation for proper functioning of the neuromuscular junction. These syndromes form part of the wider spectrum of congenital disorders of glycosylation caused by impaired asparagine-linked glycosylation. It is likely that further genes encoding components of this pathway will be associated with congenital myasthenic syndromes or impaired neuromuscular transmission as part of a more severe multisystem disorder. Our findings suggest that treatment with cholinesterase inhibitors may improve muscle function in many of the congenital disorders of glycosylation.

Electroconvulsive therapy and subsequent epilepsy in patients with affective disorders: A register-based Danish cohort study.

PubMed

Bøg, Fie Krossdal; Jørgensen, Martin Balslev; Andersen, Zorana Jovanovic; Osler, Merete

It has been suggested that Electroconvulsive Therapy (ECT) might increase the risk of epilepsy but the few patient studies with retrospective data from medical records do not support the hypothesis. The aim of this study was to examine the relationship between ECT and subsequent incident epilepsy in patients with affective disorder. We also explored whether any association varied with number of ECTs and time since last treatment. All 169,457 patients with first hospital contact for an affective disorder between January 2005 and December 2015 were identified in the Danish National Patient Registry and followed for incident epilepsy from January 2005 until November 2016. The association between ECT and epilepsy was examined using Cox proportional hazard regression with adjustment for gender, age, educational level, comorbid schizophrenia, previous stroke and antidepressant and antipsychotic medication use. A total of 5875 patients had at least one ECT and 1873 patients developed epilepsy (Incidence rate: 213 pr. 100,000 person years) during the follow-up of mean 5 years. In patients below age 40 years, ECT was associated with a higher rate of epilepsy after adjustment for covariables (Hazard Ratio (HR) = 1.84; 95% Confidence Intervals (CI) = [1.24-2.74]). In patients aged 41-60 years ECT was not associated with epilepsy, while for those above 60 treated with ECT the rate was lower (HR = 0.57; (95% CI = [0.37-0.89]). In patients with affective disorders, we found a weak positive association between ECT and subsequent diagnosis of epilepsy in those younger than 40 years, and a weak negative association in patients older than 60 years. The associations might be subject to residual confounding from risk factors related to ECT. Copyright © 2017 Elsevier Inc. All rights reserved.

HIV-associated cognitive disorders in perinatally infected children and adolescents: a novel composite cognitive domains score.

PubMed

Phillips, Nicole J; Hoare, Jacqueline; Stein, Dan J; Myer, Landon; Zar, Heather J; Thomas, Kevin G F

2018-04-22

Accurate assessment of HIV-associated cognitive disorders in perinatally infected children and adolescents is challenging. Assessments of general intellectual functioning, or global cognition, may not provide information regarding domain-specific strengths and weaknesses, and may therefore fail to detect, impaired trajectories of development within particular cognitive domains. We compare the efficacy of global cognitive scores to that of composite cognitive domain scores in detecting cognitive disorders in a sample of perinatally HIV-infected children, and a demographically matched HIV negative control group, drawn from the Cape Town Adolescent Antiretroviral Cohort (CTAAC) study. All children were administered a comprehensive neuropsychological test battery. Using data from that test battery, we created ten separate composite cognitive domains: general intellectual functioning, attention, working memory, visual memory, verbal memory, language, visual spatial ability, motor coordination, processing speed and executive function. Within each domain, each test bore a high level of association with each of the other tests in that domain (Cronbach's α ≥ .70 for all domains). We found that composite domain scores calculated on whole-sample data were significantly higher than those calculated using control-sample data. Our comparison of a global cognitive score to composite domain scores suggested that the latter provided more detailed information (regarding strengths, weaknesses, areas of impairment), and when compared to global scores, were more sensitive in detecting HIV-associated cognitive disorders, and were able to distinguish HIV-infected patients from uninfected controls. Hence, we recommend using this method of composite cognitive domains scores, rather than global aggregate scores, when assessing cognitive function in paediatric HIV. This method provides a convenient and relatively accurate assessment that might help with cross-cultural and cross-region comparisons as researchers try to detect cognitive impairment patterns in HIV-infected children and adolescents globally.

Intellectually Gifted Students with Possible Characteristics of ASD: A Multiple Case Study of Psycho-Educational Assessment Practices

ERIC Educational Resources Information Center

Burger-Veltmeijer, Agnes E. J.; Minnaert, Alexander E. M. G.; Van den Bosch, Els J.

2016-01-01

The Strengths and Weaknesses Heuristic (S&W Heuristic) was constructed in order to reduce biased assessments of students with (suspicion of) Intellectual Giftedness in co-occurrence with Autism Spectrum Disorder (IG + ASD) and to establish a well-founded interconnection between assessment data and intervention indications. The current study is…

Probed Serial Recall in Williams Syndrome: Lexical Influences on Phonological Short-Term Memory

ERIC Educational Resources Information Center

Brock, Jan; McCormack, Teresa; Boucher, Jill

2005-01-01

Williams syndrome is a genetic disorder that, it has been claimed, results in an unusual pattern of linguistic strengths and weaknesses. The current study investigated the hypothesis that there is a reduced influence of lexical knowledge on phonological short-term memory in Williams syndrome. Fourteen children with Williams syndrome and 2…

The Broader Cognitive Phenotype of Autism in Parents: How Specific Is the Tendency for Local Processing and Executive Dysfunction?

ERIC Educational Resources Information Center

Bolte, Sven; Poustka, Fritz

2006-01-01

Background: The objective of this study was to investigate the tendency for local processing style ("weak central coherence") and executive dysfunction in parents of subjects with an autism spectrum disorder (ASD) compared with parents of individuals with early onset schizophrenia (EOS) and mental retardation (MR). Method: Sixty-two…

Do Handwriting Difficulties Correlate with Core Symptomology, Motor Proficiency and Attentional Behaviours?

ERIC Educational Resources Information Center

Grace, Nicci; Enticott, Peter Gregory; Johnson, Beth Patricia; Rinehart, Nicole Joan

2017-01-01

Handwriting is commonly identified as an area of weakness in children with autism spectrum disorder (ASD), but precise deficits have not been fully characterised. Boys with ASD (n = 23) and matched controls (n = 20) aged 8-12 years completed a simple, digitised task to objectively assess handwriting performance using advanced descriptive measures.…

Investigating the Receptive-Expressive Vocabulary Profile in Children with Idiopathic ASD and Comorbid ASD and Fragile X Syndrome

ERIC Educational Resources Information Center

Haebig, Eileen; Sterling, Audra

2017-01-01

Previous work has noted that some children with autism spectrum disorder (ASD) display weaknesses in receptive vocabulary relative to expressive vocabulary abilities. The current study extended previous work by examining the receptive-expressive vocabulary profile in boys with idiopathic ASD and boys with concomitant ASD and fragile X syndrome…

Neurocognitive Approaches to Developmental Disorders of Numerical and Mathematical Cognition: The Perils of Neglecting the Role of Development

ERIC Educational Resources Information Center

Ansari, Daniel

2010-01-01

The present paper provides a critical overview of how adult neuropsychological models have been applied to the study of the atypical development of numerical cognition. Specifically, the following three assumptions are challenged: 1. Profiles of strength and weaknesses do not change over developmental time. 2. Similar neuronal structures are…

Children with Praderwilli Syndrome Vs. Williams Syndrome: Indirect Effects on Parents during a Jigsaw Puzzle Task

ERIC Educational Resources Information Center

Ly, T. M.; Hodapp, R. M.

2005-01-01

Background: Genetic disorders predispose individuals to exhibit characteristic behaviours, which in turn elicit particular behaviours from others. In response to the strength of Prader?Willi syndrome (PWS) and weakness of Williams syndrome (WS) in visual-spatial tasks such as jigsaw puzzles, parents' behaviours can be affected by their child's…

A Review of Eye Movement Desensitization and Reprocessing (EMDR): Research Findings and Implications for Counsellors.

ERIC Educational Resources Information Center

MacCluskie, Kathryn C.

1998-01-01

States that within the last six years a new therapeutic technique for the treatment of posttraumatic stress disorder, Eye Movement Desensitization and Reprocessing (EMDR), has emerged. Examines the strengths and weaknesses of published studies concerning EMDR, describes the nature of the debate about the efficacy of EMDR, and reviews implications…

Thermostatistically approaching living systems: Boltzmann Gibbs or nonextensive statistical mechanics?

NASA Astrophysics Data System (ADS)

Tsallis, Constantino

2006-03-01

Boltzmann-Gibbs ( BG) statistical mechanics is, since well over one century, successfully used for many nonlinear dynamical systems which, in one way or another, exhibit strong chaos. A typical case is a classical many-body short-range-interacting Hamiltonian system (e.g., the Lennard-Jones model for a real gas at moderately high temperature). Its Lyapunov spectrum (which characterizes the sensitivity to initial conditions) includes positive values. This leads to ergodicity, the stationary state being thermal equilibrium, hence standard applicability of the BG theory is verified. The situation appears to be of a different nature for various phenomena occurring in living organisms. Indeed, such systems exhibit a complexity which does not really accommodate with this standard dynamical behavior. Life appears to emerge and evolve in a kind of delicate situation, at the frontier between large order (low adaptability and long memory; typically characterized by regular dynamics, hence only nonpositive Lyapunov exponents) and large disorder (high adaptability and short memory; typically characterized by strong chaos, hence at least one positive Lyapunov exponent). Along this frontier, the maximal relevant Lyapunov exponents are either zero or close to that, characterizing what is currently referred to as weak chaos. This type of situation is shared by a great variety of similar complex phenomena in economics, linguistics, to cite but a few. BG statistical mechanics is built upon the entropy S=-k∑plnp. A generalization of this form, S=k(1-∑piq)/(q-1) (with S=S), has been proposed in 1988 as a basis for formulating what is nowadays currently called nonextensive statistical mechanics. This theory appears to be particularly adapted for nonlinear dynamical systems exhibiting, precisely, weak chaos. Here, we briefly review the theory, its dynamical foundation, its applications in a variety of disciplines (with special emphasis to living systems), and its connections with the ubiquitous scale-free networks.

Wigner's quantum phase-space current in weakly-anharmonic weakly-excited two-state systems

NASA Astrophysics Data System (ADS)

Kakofengitis, Dimitris; Steuernagel, Ole

2017-09-01

There are no phase-space trajectories for anharmonic quantum systems, but Wigner's phase-space representation of quantum mechanics features Wigner current J . This current reveals fine details of quantum dynamics —finer than is ordinarily thought accessible according to quantum folklore invoking Heisenberg's uncertainty principle. Here, we focus on the simplest, most intuitive, and analytically accessible aspects of J. We investigate features of J for bound states of time-reversible, weakly-anharmonic one-dimensional quantum-mechanical systems which are weakly-excited. We establish that weakly-anharmonic potentials can be grouped into three distinct classes: hard, soft, and odd potentials. We stress connections between each other and the harmonic case. We show that their Wigner current fieldline patterns can be characterised by J's discrete stagnation points, how these arise and how a quantum system's dynamics is constrained by the stagnation points' topological charge conservation. We additionally show that quantum dynamics in phase space, in the case of vanishing Planck constant ℏ or vanishing anharmonicity, does not pointwise converge to classical dynamics.

Social communication in children with autism spectrum disorder (asd): Correlation between DSM-5 and autism classification system of functioning-social communication (ACSF:SC).

PubMed

Craig, Francesco; Fanizza, Isabella; Russo, Luigi; Lucarelli, Elisabetta; Alessandro, Lorenzo; Pasca, Maria Grazia; Trabacca, Antonio

2017-07-01

The aim of this study was to classify children with Autism Spectrum Disorder (ASD) according to Autism Classification System of Functioning: Social Communication (ACSF:SC) criteria, in order to investigate the association between social communication ability, ASD severity, adaptive functioning, cognitive abilities and psychoeducational profile. The severity of social communication impairment was specified through Diagnostic and Statistical Manual of Mental Disorders-5th edition (DSM-5) and ACSF:SC tool. The ADOS-2, Vineland-II and PEP-3 were administered to all participants. We found a positive correlation between DSM-5 levels and ACSF:SC-Typical Performance (r = 0.35; P = 0.007) and ACSF:SC-Capacity (r = 0.31; P = 0.01) levels. Children included in the five levels of ACSF:SC (Typical Performance and Capacity) showed statistically significant differences in ADOS-2 (Social Affect), Vineland-II (Communication and Socialization), and PEP-3 (Communication, motor skills, maladaptive behavior) scores. The results of this study indicate that ACSF:SC provide a better understanding of functional profile of children with ASD based on the social communication abilities. Children with greater severity of social communication showed more difficulty in adaptive behavior and psychoeducational profiles. In conclusion, the ACSF:SC could help clinicians and therapists not only to understand the strength and weakness of preschool children with ASD but also to devise specific treatment in order to promote their social integration. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1249-1258. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Weak values of spin and momentum in atomic systems.

NASA Astrophysics Data System (ADS)

Flack, Robert; Hiley, Basil; Barker, Peter; Monachello, Vincenzo; Morley, Joel

2017-04-01

Weak values have a long history and were first considered by Landau and London in connection with superfluids. Hirschfelder called them sub-observables and Dirac anticipatied them when discussing non-commutative geometry in quantum mechanics. The idea of a weak value has returned to prominence due to Aharonov, Albert and Vaidman showing how they can be measured. They are not eigenvalues of the system and can not be measured by a collapse of the wave function with the traditional Von Neumann (strong) measurement which is a single stage process. In contrast the weak measurement process has three stages; preselection, weak stage and finally a post selection. Although weak values have been observed using photons and neutrons, we are building two experiments to observe weak values of spin and momentum in atomic systems. For spin we are following the method outlined by Duck et al which is a variant on the original Stern-Gerlach experiment using a metastable, 23S1 , form of helium. For momentum we are using a method similar to that used by Kocsis with excited argon atoms in the 3P2 state, passing through a 2-slit interferometer. The design, simulation and re John Fetzer Memorial Trust.

FAA computer security : concerns remain due to personnel and other continuing weaknesses

DOT National Transportation Integrated Search

2000-08-01

FAA has a history of computer security weaknesses in a number of areas, including its physical security management at facilities that house air traffic control (ATC) systems, systems security for both operational and future systems, management struct...

Reply to "Comment on `Null weak values and the past of a quantum particle"'

NASA Astrophysics Data System (ADS)

Duprey, Q.; Matzkin, A.

2018-04-01

We discuss the preceding Comment [D. Sokolovski, preceding Comment, Phys. Rev. A 97, 046102 (2018), 10.1103/PhysRevA.97.046102] and conclude that the arguments given there against the relevance of null weak values as representing the absence of a system property are not compelling. We give an example in which the transition matrix elements that make the projector weak values vanish are the same ones that suppress detector clicks in strong measurements. Whether weak values are taken to account for the past of a quantum system or not depend on general interpretational commitments of the quantum formalism itself rather than on peculiarities of the weak measurements framework.

Non-pharmacological sleep interventions for youth with chronic health conditions: a critical review of the methodological quality of the evidence.

PubMed

Brown, Cary A; Kuo, Melissa; Phillips, Leah; Berry, Robyn; Tan, Maria

2013-07-01

Restorative sleep is clearly linked with well-being in youth with chronic health conditions. This review addresses the methodological quality of non-pharmacological sleep intervention (NPSI) research for youth with chronic health conditions. The Guidelines for Critical Review (GCR) and the Effective Public Health Practice Project Quality Assessment Tool (EPHPP) were used in the review. The search yielded 31 behavioural and 10 non-behavioural NPSI for review. Most studies had less than 10 participants. Autism spectrum disorders, attention deficit/hyperactivity disorders, down syndrome, intellectual disabilities, and visual impairments were the conditions that most studies focused upon. The global EPHPP scores indicated most reviewed studies were of weak quality. Only 7 studies were rated as moderate, none were strong. Studies rated as weak quality frequently had recruitment issues; non-blinded participants/parents and/or researchers; and used outcome measures without sound psychometric properties. Little conclusive evidence exists for NPSIs in this population. However, NPSIs are widely used and these preliminary studies demonstrate promising outcomes. There have not been any published reports of negative outcomes that would preclude application of the different NPSIs on a case-by-case basis guided by clinical judgement. These findings support the need for more rigorous, applied research. • Methodological Quality of Sleep Research • Disordered sleep (DS) in youth with chronic health conditions is pervasive and is important to rehabilitation therapists because DS contributes to significant functional problems across psychological, physical and emotional domains. • Rehabilitation therapists and other healthcare providers receive little education about disordered sleep and are largely unaware of the range of assessment and non-pharmacological intervention strategies that exist. An evidence-based website of pediatric sleep resources can be found at http://www.SleepRight.ualberta.ca • The current research on non-pharmacological sleep interventions (NPSI) for youth with health conditions is methodologically weak. However, consistently positive outcomes reported in the literature demonstrate that pragmatic interventions such as bright light therapy, activity, massage and behavioral interventions are promising areas. No studies found reasons that a trail of a NPSI matched to the youth's context and condition should not attempted. More rigorous clinically relevant study of pragmatic non-pharmacological interventions appropriate for therapists' and parents' needs is required.

State-dependent rotations of spins by weak measurements

NASA Astrophysics Data System (ADS)

Miller, D. J.

2011-03-01

It is shown that a weak measurement of a quantum system produces a new state of the quantum system which depends on the prior state, as well as the (uncontrollable) measured position of the pointer variable of the weak-measurement apparatus. The result imposes a constraint on hidden-variable theories which assign a different state to a quantum system than standard quantum mechanics. The constraint means that a crypto-nonlocal hidden-variable theory can be ruled out in a more direct way than previously done.

Quantum phase transitions in effective spin-ladder models for graphene zigzag nanoribbons

NASA Astrophysics Data System (ADS)

Koop, Cornelie; Wessel, Stefan

2017-10-01

We examine the magnetic correlations in quantum spin models that were derived recently as effective low-energy theories for electronic correlation effects on the edge states of graphene nanoribbons. For this purpose, we employ quantum Monte Carlo simulations to access the large-distance properties, accounting for quantum fluctuations beyond mean-field-theory approaches to edge magnetism. For certain chiral nanoribbons, antiferromagnetic interedge couplings were previously found to induce a gapped quantum disordered ground state of the effective spin model. We find that the extended nature of the intraedge couplings in the effective spin model for zigzag nanoribbons leads to a quantum phase transition at a large, finite value of the interedge coupling. This quantum critical point separates the quantum disordered region from a gapless phase of stable edge magnetism at weak intraedge coupling, which includes the ground states of spin-ladder models for wide zigzag nanoribbons. To study the quantum critical behavior, the effective spin model can be related to a model of two antiferromagnetically coupled Haldane-Shastry spin-half chains with long-ranged ferromagnetic intrachain couplings. The results for the critical exponents are compared also to several recent renormalization-group calculations for related long-ranged interacting quantum systems.

Structure, viscoelasticity, and interfacial dynamics of a model polymeric bicontinuous microemulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hickey, Robert J.; Gillard, Timothy M.; Irwin, Matthew T.

2016-01-01

We have systematically studied the equilibrium structure and dynamics of a polymeric bicontinuous microemulsion (BμE) composed of poly(cyclohexylethylene) (PCHE), poly(ethylene) (PE), and a volumetrically symmetric PCHE–PE diblock copolymer, using dynamic mechanical spectroscopy, small angle X-ray and neutron scattering, and transmission electron microscopy. The BμE was investigated over an 80 °C temperature range, revealing a structural evolution and a rheological response not previously recognized in such systems. As the temperature is reduced below the point associated with the lamellar-disorder transition at compositions adjacent to the microemulsion channel, the interfacial area per chain of the BμE approaches that of the neat (undiluted)more » lamellar diblock copolymer. With increasing temperature, the diblock-rich interface swells through homopolymer infiltration. Time–temperature-superposed linear dynamic data obtained as a function of frequency show that the viscoelastic response of the BμE is strikingly similar to that of the fluctuating pure diblock copolymer in the disordered state, which we associate with membrane undulations and the breaking and reforming of interfaces. This work provides new insights into the structure and dynamics that characterize thermodynamically stable BμEs in the limits of relatively weak and strong segregation.« less

ETIOLOGY, TRIGGERS AND NEUROCHEMICAL CIRCUITS ASSOCIATED WITH UNEXPECTED, EXPECTED, AND LABORATORY-INDUCED PANIC ATTACKS

PubMed Central

Johnson, Philip L.; Federici, Lauren M.; Shekhar, Anantha

2014-01-01

Panic disorder (PD) is a severe anxiety disorder that is characterized by recurrent panic attacks (PA), which can be unexpected (uPA, i.e., no clear identifiable trigger) or expected (ePA). Panic typically involves an abrupt feeling of catastrophic fear or distress accompanied by physiological symptoms such as palpitations, racing heart, thermal sensations, and sweating. Recurrent uPA and ePA can also lead to agoraphobia, where subjects with PD avoid situations that were associated with PA. Here we will review recent developments in our understanding of PD, which includes discussions on: symptoms and signs associated with uPA and ePAs; Diagnosis of PD and the new DSM-V; biological etiology such as heritability and gene x environment and gene x hormonal development interactions; comparisons between laboratory and naturally occurring uPAs and ePAs; neurochemical systems that are associated with clinical PAs (e.g. gene associations; targets for triggering or treating PAs), adaptive fear and panic response concepts in the context of new NIH RDoc approach; and finally strengths and weaknesses of translational animal models of adaptive and pathological panic states. PMID:25130976

A Bragg glass phase in the vortex lattice of a type II superconductor.

PubMed

Klein, T; Joumard, I; Blanchard, S; Marcus, J; Cubitt, R; Giamarchi, T; Le Doussal, P

2001-09-27

Although crystals are usually quite stable, they are sensitive to a disordered environment: even an infinitesimal amount of impurities can lead to the destruction of crystalline order. The resulting state of matter has been a long-standing puzzle. Until recently it was believed to be an amorphous state in which the crystal would break into 'crystallites'. But a different theory predicts the existence of a novel phase of matter: the so-called Bragg glass, which is a glass and yet nearly as ordered as a perfect crystal. The 'lattice' of vortices that contain magnetic flux in type II superconductors provide a good system to investigate these ideas. Here we show that neutron-diffraction data of the vortex lattice provides unambiguous evidence for a weak, power-law decay of the crystalline order characteristic of a Bragg glass. The theory also predicts accurately the electrical transport properties of superconductors; it naturally explains the observed phase transitions and the dramatic jumps in the critical current associated with the melting of the Bragg glass. Moreover, the model explains experiments as diverse as X-ray scattering in disordered liquid crystals and the conductivity of electronic crystals.

Mad genius revisited: Vulnerability to psychopathology, biobehavioral approach-avoidance, and creativity.

PubMed

Baas, Matthijs; Nijstad, Bernard A; Boot, Nathalie C; De Dreu, Carsten K W

2016-06-01

Although many believe that creativity associates with a vulnerability to psychopathology, research findings are inconsistent. Here we address this possible linkage between risk of psychopathology and creativity in nonclinical samples. We propose that propensity for specific psychopathologies can be linked to basic motivational approach and avoidance systems, and that approach and avoidance motivation differentially influences creativity. Based on this reasoning, we predict that propensity for approach-based psychopathologies (e.g., positive schizotypy and risk of bipolar disorder) associates with increased creativity, whereas propensity for avoidance-based psychopathologies (e.g., anxiety, negative schizotypy, and depressive mood) associates with reduced creativity. Previous meta-analyses resonate with this proposition and showed small positive relations between positive schizotypy and creativity and small negative relations between negative schizotypy and creativity and between anxiety and creativity. To this we add new meta-analytic findings showing that risk of bipolar disorder (e.g., hypomania, mania) positively associates with creativity (k = 28, r = .224), whereas depressive mood negatively associates (albeit weakly) with creativity (k = 39, r = -.064). Our theoretical framework, along with the meta-analytic results, indicates when and why specific psychopathologies, and their inclinations, associate with increased or, instead, reduced creativity. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Immunological research in clinical psychiatry: report on the consensus debate during the 7th Expert Meeting on Psychiatry and Immunology.

PubMed

Arolt, V; Rothermundt, M; Peters, M; Leonard, B

2002-01-01

There is convincing evidence that cytokines are involved in the physiology and pathophysiology of brain function and interact with different neurotransmitter and neuroendocrine pathways. The possible involvement of the immune system in the neurobiological mechanisms that underlie psychiatric disorders has attracted increasing attention in recent years. Thus in the last decade, numerous clinical studies have demonstrated dysregulated immune functions in patients with psychiatric disorders. Such findings formed the basis of the 7th Expert Meeting on Psychiatry and Immunology in Muenster, Germany, where a consensus symposium was held to consider the strengths and weaknesses of current research in psychoneuroimmunology. Following a general overview of the field, the following topics were discussed: (1) methodological problems in laboratory procedures and recruitment of clinical samples; (2) the importance of pre-clinical research and animal models in psychiatric research; (3) the problem of statistical vs biological relevance. It was concluded that, despite a fruitful proliferation of research activities throughout the last decade, the continuous elaboration of methodological standards including the implementation of hypothesis-driven research represents a task that is likely to prove crucial for the future development of immunology research in clinical psychiatry.

Parent–Youth Agreement on Self-Reported Competencies of Youth With Depressive and Suicidal Symptoms

PubMed Central

Mbekou, Valentin; MacNeil, Sasha; Gignac, Martin; Renaud, Johanne

2015-01-01

Objective: A multi-informant approach is often used in child psychiatry. The Achenbach System of Empirically Based Assessment uses this approach, gathering parent reports on the Child Behaviour Checklist (CBCL) and youth reports on the Youth Self-Report (YSR), which contain scales assessing both the child’s problems and competencies. Agreement between parent and youth perceptions of their competencies on these forms has not been studied to date. Method: Our study examined the parent–youth agreement of competencies on the CBCL and YSR from a sample of 258 parent–youth dyads referred to a specialized outpatient clinic for depressive and suicidal disorders. Intraclass correlation coefficients were calculated for all competency scales (activity, social, and academic), with further examinations based on youth’s sex, age, and type of problem. Results: Weak-to-moderate parent–youth agreements were reported on the activities and social subscales. For the activities subscale, boys’ ratings had a strong correlation with parents’ ratings, while it was weak for girls. Also, agreement on activities and social subscales was stronger for dyads with the youth presenting externalizing instead of internalizing problems. Conclusion: Agreement on competencies between parents and adolescents varied based on competency and adolescent sex, age, and type of problem. PMID:25886673

New trace element determinations in the fingernails of ALS patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Dalsem, D.J.; Ehmann, W.D.; Robinson, L.

1996-12-31

Amyotrophic lateral sclerosis (ALS) afflicts 2 of every 100,000 people in the United States each year. A well-known example of ALS today is Stephen Hawking. He is a theoretical physicist, the author of A Brief History of Time, and is virtually immobilized by ALS. Diseases that cause progressive paralysis because of motor neuron degeneration in the central nervous system are termed motor neuron disorders (MND). Amyotrophic lateral sclerosis is a common form of MND. Pain-free, progressive muscular weakness is the most common clinical symptom. There is chronic weakness with atrophy of the affected muscles by the time the disease ismore » diagnosed. Atrophy eventually results in wheelchair confinement and then only bed without the ability to speak or swallow. Death often occurs as a result of respiratory problems. Unlike other neurodegenerative diseases, in ALS the patient`s bladder and bowel control, eye movement, and mental faculties are preserved. The question today is whether or not certain trace elements are involved in the etiology or pathogenesis of ALS. A collaborative study was undertaken by the University of Kentucky and Oak Ridge National Laboratory (ORNL) using neutron activation analysis (NAA) to study trace element concentrations in ALS patients fingernails to determine if there existed statistically significant imbalances.« less

Congenital Myasthenic Syndromes or Inherited Disorders of Neuromuscular Transmission: Recent Discoveries and Open Questions

PubMed Central

Nicole, Sophie; Azuma, Yoshiteru; Bauché, Stéphanie; Eymard, Bruno; Lochmüller, Hanns; Slater, Clarke

2017-01-01

Congenital myasthenic syndromes (CMS) form a heterogeneous group of rare diseases characterized by fatigable muscle weakness. They are genetically-inherited and caused by defective synaptic transmission at the cholinergic neuromuscular junction (NMJ). The number of genes known to cause CMS when mutated is currently 30, and the relationship between fatigable muscle weakness and defective functions is quite well-understood for many of them. However, some of the most recent discoveries in individuals with CMS challenge our knowledge of the NMJ, where the basis of the pathology has mostly been investigated in animal models. Frontier forms between CMS and congenital myopathy, which have been genetically and clinically identified, underline the poorly understood interplay between the synaptic and extrasynaptic molecules in the neuromuscular system. In addition, precise electrophysiological and histopathological investigations of individuals with CMS suggest an important role of NMJ plasticity in the response to CMS pathogenesis. While efficient drug-based treatments are already available to improve neuromuscular transmission for most forms of CMS, others, as well as neurological and muscular comorbidities, remain resistant. Taken together, the available pathological data point to physiological issues which remain to be understood in order to achieve precision medicine with efficient therapeutics for all individuals suffering from CMS. PMID:29125502

Phonon assisted carrier motion on the Wannier-Stark ladder

NASA Astrophysics Data System (ADS)

Cheung, Alfred; Berciu, Mona

2014-03-01

It is well known that at zero temperature and in the absence of electron-phonon coupling, the presence of an electric field leads to localization of carriers residing in a single band of finite bandwidth. In this talk, we will present an implementation of the self-consistent Born approximation (SCBA) to study the effect of weak electron-phonon coupling on the motion of a carrier in a biased system. At moderate and strong electron-phonon coupling, we supplement the SCBA, describing the string of phonons left behind by the carrier, with the momentum average approximation to describe the phonon cloud that accompanies the resulting polaron. We find that coupling to the lattice delocalizes the carrier, as expected, although long-lived resonances resulting from the Wannier-Stark states of the polaron may appear in certain regions of the parameter space. We end with a discussion of how our method can be improved to model disorder, other types of electron-phonon coupling, and electron-hole pair dissociation in a biased system.

Unconventional Bose—Einstein Condensations from Spin-Orbit Coupling

NASA Astrophysics Data System (ADS)

Wu, Cong-Jun; Ian, Mondragon-Shem; Zhou, Xiang-Fa

2011-09-01

According to the “no-node" theorem, the many-body ground state wavefunctions of conventional Bose—Einstein condensations (BEC) are positive-definite, thus time-reversal symmetry cannot be spontaneously broken. We find that multi-component bosons with spin-orbit coupling provide an unconventional type of BECs beyond this paradigm. We focus on a subtle case of isotropic Rashba spin-orbit coupling and the spin-independent interaction. In the limit of the weak confining potential, the condensate wavefunctions are frustrated at the Hartree—Fock level due to the degeneracy of the Rashba ring. Quantum zero-point energy selects the spin-spiral type condensate through the “order-from-disorder" mechanism. In a strong harmonic confining trap, the condensate spontaneously generates a half-quantum vortex combined with the skyrmion type of spin texture. In both cases, time-reversal symmetry is spontaneously broken. These phenomena can be realized in both cold atom systems with artificial spin-orbit couplings generated from atom-laser interactions and exciton condensates in semi-conductor systems.

Branched flow and caustics in random media with magnetic fields

NASA Astrophysics Data System (ADS)

Metzger, Jakob; Fleischmann, Ragnar; Geisel, Theo

2009-03-01

Classical particles as well as quantum mechanical waves exhibit complex behaviour when propagating through random media. One of the dominant features of the dynamics in correlated, weak disorder potentials is the branching of the flow. This can be observed in several physical systems, most notably in the electron flow in two-dimensional electron gases [1], and has also been used to describe the formation of freak waves [2]. We present advances in the theoretical understanding and numerical simulation of classical branched flows in magnetic fields. In particular, we study branching statistics and branch density profiles. Our results have direct consequences for experiments which measure transport properties in electronic systems [3].[1] e.g. M. A. Topinka et al., Nature 410, 183 (2001), M. P. Jura et al., Nature Physics 3, 841 (2007)[2] E. J. Heller, L. Kaplan and A. Dahlen, J. Geophys. Res., 113, C09023 (2008)[3] J. J. Metzger, R. Fleischmann and T. Geisel, in preparation

Recessive variants of MuSK are associated with late onset CMS and predominant limb girdle weakness.

PubMed

Owen, David; Töpf, Ana; Preethish-Kumar, Veeramani; Lorenzoni, Paulo José; Vroling, Bas; Scola, Rosana Herminia; Dias-Tosta, Elza; Geraldo, Argemiro; Polavarapu, Kiran; Nashi, Saraswati; Cox, Daniel; Evangelista, Teresinha; Dawson, John; Thompson, Rachel; Senderek, Jan; Laurie, Steven; Beltran, Sergi; Gut, Marta; Gut, Ivo; Nalini, Atchayaram; Lochmüller, Hanns

2018-04-28

Congenital myasthenic syndrome (CMS) is a heterogeneous disorder that causes fatigable muscle weakness. CMS has been associated with variants in the MuSK gene and, to date, 16 patients have been reported. MuSK-CMS patients present a different phenotypic pattern of limb girdle weakness. Here, we describe four additional patients and discuss the phenotypic and clinical relationship with those previously reported. Two novel damaging missense variants are described: c.1742T > A; p.I581N found in homozygosis, and c.1634T > C; p.L545P found in compound heterozygosis with p.R166*. The reported patients had predominant limb girdle weakness with symptom onset at 12, 17, 18, and 30 years of age, and the majority exhibited a good clinical response to Salbutamol therapy, but not to esterase inhibitors. Meta-analysis including previously reported variants revealed an increased likelihood of a severe, respiratory phenotype with null alleles. Missense variants exclusively affecting the kinase domain, but not the catalytic site, are associated with late onset. These data refine the phenotype associated with MuSK-related CMS. © 2018 Wiley Periodicals, Inc.

Agrin mutations lead to a congenital myasthenic syndrome with distal muscle weakness and atrophy.

PubMed

Nicole, Sophie; Chaouch, Amina; Torbergsen, Torberg; Bauché, Stéphanie; de Bruyckere, Elodie; Fontenille, Marie-Joséphine; Horn, Morten A; van Ghelue, Marijke; Løseth, Sissel; Issop, Yasmin; Cox, Daniel; Müller, Juliane S; Evangelista, Teresinha; Stålberg, Erik; Ioos, Christine; Barois, Annie; Brochier, Guy; Sternberg, Damien; Fournier, Emmanuel; Hantaï, Daniel; Abicht, Angela; Dusl, Marina; Laval, Steven H; Griffin, Helen; Eymard, Bruno; Lochmüller, Hanns

2014-09-01

Congenital myasthenic syndromes are a clinically and genetically heterogeneous group of rare diseases resulting from impaired neuromuscular transmission. Their clinical hallmark is fatigable muscle weakness associated with a decremental muscle response to repetitive nerve stimulation and frequently related to postsynaptic defects. Distal myopathies form another clinically and genetically heterogeneous group of primary muscle disorders where weakness and atrophy are restricted to distal muscles, at least initially. In both congenital myasthenic syndromes and distal myopathies, a significant number of patients remain genetically undiagnosed. Here, we report five patients from three unrelated families with a strikingly homogenous clinical entity combining congenital myasthenia with distal muscle weakness and atrophy reminiscent of a distal myopathy. MRI and neurophysiological studies were compatible with mild myopathy restricted to distal limb muscles, but decrement (up to 72%) in response to 3 Hz repetitive nerve stimulation pointed towards a neuromuscular transmission defect. Post-exercise increment (up to 285%) was observed in the distal limb muscles in all cases suggesting presynaptic congenital myasthenic syndrome. Immunofluorescence and ultrastructural analyses of muscle end-plate regions showed synaptic remodelling with denervation-reinnervation events. We performed whole-exome sequencing in two kinships and Sanger sequencing in one isolated case and identified five new recessive mutations in the gene encoding agrin. This synaptic proteoglycan with critical function at the neuromuscular junction was previously found mutated in more typical forms of congenital myasthenic syndrome. In our patients, we found two missense mutations residing in the N-terminal agrin domain, which reduced acetylcholine receptors clustering activity of agrin in vitro. Our findings expand the spectrum of congenital myasthenic syndromes due to agrin mutations and show an unexpected correlation between the mutated gene and the associated phenotype. This provides a good rationale for examining patients with apparent distal myopathy for a neuromuscular transmission disorder and agrin mutations. © The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rescriptive and Descriptive Gauge Symmetry in Finite-Dimensional Dynamical Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurfil, Pini

2007-02-07

Gauge theories in physics constitute a fundamental tool for modeling interactions among electromagnetic, weak and strong forces. They have been used in a myriad of fields, ranging from sub-atomic physics to cosmology. The basic mathematical tool generating the gauge theories is that of symmetry, i.e. a redundancy in the description of the system. Although symmetries have long been recognized as a fundamental tool for solving ordinary differential equations, they have not been formally categorized as gauge theories. In this paper, we show how simple systems described by ordinary differential equations are prone to exhibit gauge symmetry, and discuss a fewmore » practical applications of this approach. In particular, we utilize the notion of gauge symmetry to question some common engineering misconceptions of chaotic and stochastic phenomena, and show that seemingly 'disordered' (deterministic) or 'random' (stochastic) behaviors can be 'ordered'. This brings into play the notion of observation; we show that temporal observations may be misleading when used for chaos detection. From a practical standpoint, we use gauge symmetry to considerably mitigate the numerical truncation error of numerical integrations.« less

Oxidative Stress and Neurodegenerative Disorders

PubMed Central

Li, Jie; O, Wuliji; Li, Wei; Jiang, Zhi-Gang; Ghanbari, Hossein A.

2013-01-01

Living cells continually generate reactive oxygen species (ROS) through the respiratory chain during energetic metabolism. ROS at low or moderate concentration can play important physiological roles. However, an excessive amount of ROS under oxidative stress would be extremely deleterious. The central nervous system (CNS) is particularly vulnerable to oxidative stress due to its high oxygen consumption, weakly antioxidative systems and the terminal-differentiation characteristic of neurons. Thus, oxidative stress elicits various neurodegenerative diseases. In addition, chemotherapy could result in severe side effects on the CNS and peripheral nervous system (PNS) of cancer patients, and a growing body of evidence demonstrates the involvement of ROS in drug-induced neurotoxicities as well. Therefore, development of antioxidants as neuroprotective drugs is a potentially beneficial strategy for clinical therapy. In this review, we summarize the source, balance maintenance and physiologic functions of ROS, oxidative stress and its toxic mechanisms underlying a number of neurodegenerative diseases, and the possible involvement of ROS in chemotherapy-induced toxicity to the CNS and PNS. We ultimately assess the value for antioxidants as neuroprotective drugs and provide our comments on the unmet needs. PMID:24351827