480 research outputs found
Expanding the etiologic spectrum of spastic ataxia syndrome: chronic infection with human T lymphotropic virus type 1
Infection with human T cell lymphotropic virus type 1 (HTLV-1) is in most cases indolent; however, some patients develop adult T cell leukemia, associated with poor prognosis, or the highly disabling and incurable HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) (Verdonck et al. 2007; Cooper et al. 2009). HTLV-1 is an endemic infection in Southern Japan, Iran, South America, the Caribbean basin, West Africa, and among aborigines in Australia (Verdonck et al. 2007). There are no established biomarkers to predict complications in HTLV-1; however, the percentage of peripheral blood mononuclear cells (PBMCs) harboring the provirus, called proviral load (PVL), and beta-2 microglobulin (β2M) in serum are surrogate biomarkers. Associations with neurological syndromes other than HAM/TSP have been claimed, including neuropathy, motor neuron disease (Araujo et al. 2019), as well as cerebellar ataxia (Iwasaki 4,5,6,; Kira et al. 1993; Gracia et al. 1995; e-1 to e-6). In the majority of reported cases, ataxia occurred in Japanese patients with HAM/TSP (Iwasaki 1990; Iwanaga 1993; Kira et al. 1993; e1, e-2, e-4, e-6). Here, we present an Iranian HTLV-1 positive patient with a cerebellar syndrome, elevated β2M in serum, and elevated neopterin and CXCL10 in cerebrospinal fluid (CSF)
Numerical Study of Aging in the Generalized Random Energy Model
Magnetizations are introduced to the Generalized Random Energy Model (GREM)
and numerical simulations on ac susceptibility is made for direct comparison
with experiments in glassy materials. Prominent dynamical natures of spin
glasses, {\it i.e.}, {\em memory} effect and {\em reinitialization}, are
reproduced well in the GREM. The existence of many layers causing continuous
transitions is very important for the two natures. Results of experiments in
other glassy materials such as polymers, supercooled glycerol and orientational
glasses, which are contrast to those in spin glasses, are interpreted well by
the Single-layer Random Energy Model.Comment: 8 pages, 9 figures, to be submitted to J. Phys. Soc. Jp
Memory and chaos in an Ising spin glass
The non-equilibrium dynamics of the model 3d-Ising spin glass
- FeMnTiO - has been investigated from the temperature
and time dependence of the zero field cooled magnetization recorded under
certain thermal protocols. The results manifest chaos, rejuvenation and memory
features of the equilibrating spin configuration that are very similar to those
observed in corresponding studies of the archetypal RKKY spin glass Ag(Mn). The
sample is rapidly cooled in zero magnetic field, and the magnetization recorded
on re-heating. When a stop at constant temperature is made during the
cooling, the system evolves toward its equilibrium state at this temperature.
The equilibrated state established during the stop becomes frozen in on further
cooling and is retrieved on re-heating. The memory of the aging at is not
affected by a second stop at a lower temperature
. Reciprocally, the first equilibration at has no influence on
the relaxation at , as expected within the droplet model for domain
growth in a chaotic landscape.Comment: REVTeX style; 4 pages, 4 figure
Relaxation of the field-cooled magnetization of an Ising spin glass
The time and temperature dependence of the field-cooled magnetization of a
three dimensional Ising spin glass, Fe_{0.5}Mn_{0.5}TiO_{3}, has been
investigated. The temperature and cooling rate dependence is found to exhibit
memory phenomena that can be related to the memory behavior of the low
frequency ac-susceptibility. The results add some further understanding on how
to model the three dimensional Ising spin glass in real space.Comment: 8 pages RevTEX, 5 figure
New neonatal porcine diarrhoea syndrome in Danish pigs. Characterisation of viral findings in diseased and healthy control animals
Strong rejuvenation in a chiral-glass superconductor
The glassy paramagnetic Meissner phase of a BiSrCaCuO
superconductor ( = 8.18) is investigated by squid magnetometry, using
``dc-memory'' experiments employed earlier to study spin glasses. The
temperature dependence of the zero-field-cooled and thermo-remanent
magnetization is recorded on re-heating after specific cooling protocols, in
which single or multiple halts are performed at constant temperatures. The
'spin' states equilibrated during the halts are retrieved on re-heating. The
observed memory and rejuvenation effects are similar to those observed in
Heisenberg-like spin glasses.Comment: REVTeX 4 style; 5 pages, 5 figure
Phenomenological glass model for vibratory granular compaction
A model for weakly excited granular media is derived by combining the free
volume argument of Nowak et al. [Phys. Rev. E 57, 1971 (1998)] and the
phenomenological model for supercooled liquids of Adam and Gibbs [J. Chem.
Phys. 43, 139 (1965)]. This is made possible by relating the granular
excitation parameter \Gamma, defined as the peak acceleration of the driving
pulse scaled by gravity, to a temperature-like parameter \eta(\Gamma). The
resulting master equation is formally identical to that of Bouchaud's trap
model for glasses [J. Phys. I 2, 1705 (1992)]. Analytic and simulation results
are shown to compare favourably with a range of known experimental behaviour.
This includes the logarithmic densification and power spectrum of fluctuations
under constant \eta, the annealing curve when \eta is varied cyclically in
time, and memory effects observed for a discontinuous shift in \eta. Finally,
we discuss the physical interpretation of the model parameters and suggest
further experiments for this class of systems.Comment: 2 references added; some figure labels tweaked. To appear in PR
Cerebrospinal Fluid Metals and the Association with Cerebral Small Vessel Disease
BACKGROUND: Brain metal homeostasis is essential for brain health, and deregulation can result in oxidative stress on the brain parenchyma. OBJECTIVE: Our objective in this study was to focus on two hemorrhagic MRI manifestations of small vessel disease [cerebral microbleeds (CMBs) and cortical superficial siderosis (cSS)] and associations with cerebrospinal fluid (CSF) iron levels. In addition, we aimed to analyze CSF biomarkers for dementia and associations with CSF metal levels. METHODS: This is a cross-sectional study of 196 patients who underwent memory clinic investigation, including brain MRI. CSF was collected and analyzed for metals, amyloid-β (Aβ) 42, total tau (T-tau), and phosphorylated tau (P-tau), and CSF/serum albumin ratios. Statistical analyses were performed using generalized linear models. RESULTS: No significant difference was found between CSF metal levels across diagnostic groups. Higher iron and copper levels were associated with higher CSF levels of Aβ42, T-tau, P-tau, and CSF/serum albumin ratios (p < 0.05). Zinc was associated with higher CSF/serum albumin ratios. There was no significant association between CMBs or cSS and CSF iron levels. An increase in CSF iron with the number of CMBs was seen in APOEɛ4 carriers. CONCLUSION: CSF iron levels are elevated with cerebral microbleeds in APOEɛ4 carriers, with no other association seen with hemorrhagic markers of small vessel disease. The association of elevated CSF iron and copper with tau could represent findings of increased neurodegeneration in these patients
Corrections to Scaling for the Two-dimensional Dynamic XY Model
With large-scale Monte Carlo simulations, we confirm that for the
two-dimensional XY model, there is a logarithmic correction to scaling in the
dynamic relaxation starting from a completely disordered state, while only an
inverse power law correction in the case of starting from an ordered state. The
dynamic exponent is .Comment: to appear as a Rapid commu. in Phys. Rev.
Monte Carlo Simulations of Short-time Critical Dynamics with a Conserved Quantity
With Monte Carlo simulations, we investigate short-time critical dynamics of
the three-dimensional anti-ferromagnetic Ising model with a globally conserved
magnetization (not the order parameter). From the power law behavior of
the staggered magnetization (the order parameter), its second moment and the
auto-correlation, we determine all static and dynamic critical exponents as
well as the critical temperature. The universality class of is the same
as that without a conserved quantity, but the universality class of non-zero
is different.Comment: to appear in Phys. Rev.
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