Brainstem Reflexes in Idiopathic Cervical Dystonia: Does Medullary Dysfunction Play a Role?

Background: Neurophysiological markers in dystonia have so far not been sistematically applied in clinical practice due to limited reproducibility of results and low correlations with clinical findings. Exceptions might be represented by the blink reflex (BR), including its recovery cycle (BRRC) and the trigemino-cervical reflex (TCR) which, compared to other neurophysiological methods, have shown more consistent alterations in cervical dystonia (CD). However, a comparison between the two techniques, and their possible correlation with disease symptoms, have not been thoroughly investigated. Objectives: To assess the role of BR, BRCC and TCR in the pathophysiology of idiopathic cervical dystonia. Methods: Fourteen patients and 14 age-matched healthy controls (HC) were recruited. Neurophysiological outcome measures included latency of R1 and R2 components of the BR, R2 amplitude, BRRC, latency and amplitude of P19/N31 complex of TCR. Clinical and demographic features of patients were also collected, including age at disease onset, disease duration, presence of tremor, sensory trick and pain. The Toronto Western Spasmodic Torticollis Rating Scale was used to characterize dystonia. Results: Compared to HC, CD patients showed increased latency of the BR R2 and decreased suppression of the BRRC. They also showed increased latency of the P19 and decreased amplitude of P19/N31 complex of TCR. The latency of P19 component of TCR was positively correlated with disease duration. Conclusions: We propose that the increased latency of R2 and P19 observed here might be reflective of brainstem dysfunction, mediated either by local interneuronal excitability changes or by subtle structural damage

Local Neumann semitransparent layers: Resummation, pair production, and duality

We consider local semitransparent Neumann boundary conditions for a quantum scalar field as imposed by a quadratic coupling to a source localized on a flat codimension-one surface. Upon a proper regularization to give meaning to the interaction, we interpret the effective action as a theory in a first-quantized phase space. We compute the relevant heat kernel to all order in a homogeneous background and quadratic order in perturbations, giving a closed expression for the corresponding effective action in D=4. In the dynamical case, we analyze the pair production caused by a harmonic perturbation and a Sauter pulse. Notably, we prove the existence of a strong/weak duality that links this Neumann field theory to the analog Dirichlet one.Fil: Ahmadiniaz, N.. Helmholtz-Zentrum Dresden-Rossendorf; AlemaniaFil: Franchino Viñas, Sebastián Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Manzo, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Mazzitelli, Francisco Diego. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin

The broad-band X-ray spectrum of the dipping Low Mass X-ray Binary EXO0748--676

We present results of a 0.1-100 keV BeppoSAX observation of the dipping LMXRB EXO 0748-676 performed in 2000 November. During the observation the source exhibited X-ray eclipses, type I X-ray bursts and dipping activity over a wide range of orbital phases. The 0.1-100keV "dip-free"(ie. dipping and eclipsing intervals excluded) spectrum is complex,especially at low-energies where a soft excess is present. Two very different spectral models give satisfactory fits. The first is the progressive covering model, consisting of separately absorbed black body and cut-off power-law components.The second model is an absorbed cut-off power-law together with a moderately ionized absorber with a sub-solar abundance of Fe and a 2.13 keV absorption feature (tentatively identified with Si xiii). This ionized absorber may be the same feature as seen by Chandra during dips from EXO 0748-676.Comment: 7 pages, 5 figures, paper accepted for publication in Astronomy and Astrophysic

Managing acute malnutrition in infants aged less than six months: a qualitative assessment in Niger public hospitals

Quality management of severe acute malnutrition (SAM) in infants < 6 months of age is a key strategy within the “1000 days window of opportunity”. It prevents early child death, secures optimal growth and forms a foundation for full adulthood potentials. Most studies to date on management of SAM in infants relied on informants from Non-Governmental Organizations staff or government public health officials but little is known from hospital practitioners. From June to August 2013, a qualitative appraisal of hospital practitioners’ views on the current quality of care for malnourished infants was conducted in the eight main hospitals of Niger. These eight hospitals included two National Referral Hospitals (Lamordé and Zinder) and six Regional Referral Hospitals (Poudrière, Dosso, Tahoua, Maradi, Diffa and Agadez). Authorization for the review was given by the Ministry of Health of Niger. Health workers (HW) present during surveyors’ visits were included in the study. Two (2) specific objectives were considered: 1) Determine HW perceptions and current use of the Supplemental Suckling Technique (SST) and 2) Collect HW propositions on feasibility to organize outpatient treatment of SAM in infants less than six months. Self-designed interview guide was used. Data were analysed manually and saturation in the occurrence of responses were the criteria used to retain items. The Supplemental Suckling Technique (SST), though firmly recommended by national guidelines to ensure continuation of breastfeeding and adequate nutrients intake from supplemental milks especially in a small infant, was rarely used. Main reasons advanced by staff were work overload, inadequate training, and lack of compliance from mothers. Before being discharged from hospital, mothers were counseled on continuation of treatment, follow up visits at peripheral health center (PHC) and feeding options at home. However, hospital staff had no indication whether mothers were seen at the referred PHC, nor if counseling was practiced at home. The proposed outpatient treatment model for selected cases without medical complications should relieve hospital caseloads, strengthen referral and improve breastfeeding support to mothers after discharge from hospital.Keywords: Malnutrition, infant feeding, inpatient treatment, qualitative assessment, Nige

A simple solution to mitigate noise effects in time-redundant sequences of small baseline multi-look DInSAR interferograms

We present a simple and effective filtering algorithm to mitigate noise effects in a time-redundant sequence of multi-look small baseline (SB) differential synthetic aperture radar (SAR) interferograms by exploiting the temporal relationships among the selected interferometric data pairs. The proposed method relies on the estimation of the (wrapped) filtered phase terms associated to each SAR acquisition; this result is achieved via a non-linear minimization procedure which is applied to the phase signal of conventional multi-look interferograms without any pixel selection process, and with no a-priori information on the statistics of the involved complex-valued SAR images. Following their estimation, the phase images are paired to reconstruct a new sequence of filtered SB differential interferograms, which are used to generate surface deformation products, such as deformation velocity maps and displacement time-series. The filtering algorithm effectiveness is demonstrated by analysing a set of SAR images..

Investigating the effects of transcranial alternating current stimulation on primary somatosensory cortex

Near-threshold tactile stimuli perception and somatosensory temporal discrimination threshold (STDT) are encoded in the primary somatosensory cortex (S1) and largely depend on alpha and beta S1 rhythm. Transcranial alternating current stimulation (tACS) is a non-invasive neurophysiological technique that allows cortical rhythm modulation. We investigated the effects of tACS delivered over S1 at alpha, beta, and gamma frequencies on near-threshold tactile stimuli perception and STDT, as well as phase-dependent tACS effects on near-threshold tactile stimuli perception in healthy subjects. In separate sessions, we tested the effects of different tACS montages, and tACS at the individualised S1 μ-alpha frequency peak, on STDT and near-threshold tactile stimuli perception. We found that tACS applied over S1 at alpha, beta, and gamma frequencies did not modify STDT or near-threshold tactile stimuli perception. Moreover, we did not detect effects of tACS phase or montage. Finally, tACS did not modify near-threshold tactile stimuli perception and STDT even when delivered at the individualised μ-alpha frequency peak. Our study showed that tACS does not alter near-threshold tactile stimuli or STDT, possibly due to the inability of tACS to activate deep S1 layers. Future investigations may clarify tACS effects over S1 in patients with focal dystonia, whose pathophysiology implicates increased STDT

Metastability for reversible probabilistic cellular automata with self--interaction

The problem of metastability for a stochastic dynamics with a parallel updating rule is addressed in the Freidlin--Wentzel regime, namely, finite volume, small magnetic field, and small temperature. The model is characterized by the existence of many fixed points and cyclic pairs of the zero temperature dynamics, in which the system can be trapped in its way to the stable phase. %The characterization of the metastable behavior %of a system in the context of parallel dynamics is a very difficult task, %since all the jumps in the configuration space are allowed. Our strategy is based on recent powerful approaches, not needing a complete description of the fixed points of the dynamics, but relying on few model dependent results. We compute the exit time, in the sense of logarithmic equivalence, and characterize the critical droplet that is necessarily visited by the system during its excursion from the metastable to the stable state. We need to supply two model dependent inputs: (1) the communication energy, that is the minimal energy barrier that the system must overcome to reach the stable state starting from the metastable one; (2) a recurrence property stating that for any configuration different from the metastable state there exists a path, starting from such a configuration and reaching a lower energy state, such that its maximal energy is lower than the communication energy

Timing and spectral changes of the Be X-ray transient EXO 0531-6609.2 through high and low state

We report on spectral and timing analysis of BeppoSAX data of the 13.6 s period transient X-ray pulsar EXO 0531-6609.2. Observations were carried out in March 1997 and October 1998, catching the source during a high and a low emission state, respectively. Correspondingly, the X-ray luminosity is found at a level of 4.2x10^37 erg/s and 1.5x10^36 erg/s in the two states. In the high state the X-ray emission in the energy range 1-100 keV is well fitted by an absorbed power-law with photon index Gamma ~1.7 plus a blackbody component with a characteristic temperature of ~3.5 keV. Moreover, we find an evidence of an iron emission at ~6.8 keV, typical feature in this class of sources but never revealed before in the EXO 0531-6609.2 spectrum. In the low state an absorbed power-law with Gamma ~0.4 is sufficient to fit the 1-10 keV data. During BeppoSAX observations EXO 0531-6609.2 display variations of the pulse profile with the X-ray flux: it showed single peaked and double peaked profiles in the low and high state, respectively. Based on these two observations we infer a spin-up period derivative of -(1.14+/-0.08)x10^-10 s/s. By comparing these with other period measurements reported in literature we find an alternating spin-up and spin-down behaviour that correlates well with the X-ray luminosity.Comment: 6 pages, 8 figures, A&

Relaxation Height in Energy Landscapes: an Application to Multiple Metastable States

The study of systems with multiple (not necessarily degenerate) metastable states presents subtle difficulties from the mathematical point of view related to the variational problem that has to be solved in these cases. We introduce the notion of relaxation height in a general energy landscape and we prove sufficient conditions which are valid even in presence of multiple metastable states. We show how these results can be used to approach the problem of multiple metastable states via the use of the modern theories of metastability. We finally apply these general results to the Blume--Capel model for a particular choice of the parameters ensuring the existence of two multiple, and not degenerate in energy, metastable states