263 research outputs found
Serum Compounds of Energy Metabolism Impairment Are Related to Disability, Disease Course and Neuroimaging in Multiple Sclerosis
Multiple sclerosis (MS) is characterized by primary inflammation, demyelination, and progressive neurodegeneration. A biochemical MS feature is neuronal mitochondrial dysfunction, compensated by anaerobic metabolism increase, likely aggravating progression of neurodegeneration. Here, we characterized a pragmatic serum profile of compounds related to mitochondrial energy metabolism of potential clinical use. Blood samples of 518 well characterized (disability, disease course) MS patients and 167 healthy controls were analyzed for serum purines, pyrimidines, creatinine, and lactate. Nine of the 15 compounds assayed, hypoxanthine, xanthine, uric acid, inosine, uracil, β-pseudouridine, uridine, creatinine, and lactate, differed significantly between MS patients and controls (p < 0.0001). Using these nine compounds, a unifying Biomarker Score was calculated. Controls and MS patients had mean Biomarker Scores of 0.4 ± 0.7 and 4.4 ± 1.9, respectively (p < 0.00001). The Biomarker Score was higher in patients with progressive (6.0 ± 1.8 than with relapsing remitting disease course (3.6 ± 1.5, p < 0.00001). High association between the Biomarker Score and increase in disability (EDSS) was also observed. Additionally, in 50 patients who underwent magnetic resonance imaging (MRI), increase in the Biomarker Score correlated to neuroanatomical alterations. These results, obtained in a large cohort of MS patients evaluated for serum metabolic compounds connected to energy metabolism, demonstrated that the Biomarker Score might represent a pragmatic, resource saving, easy to obtain, laboratory tool useful to monitor MS patients and predict at an early stage who will switch from an RR to a progressive disease course. For the first time, it was also clearly shown a link between mitochondrial dysfunction and MRI lesions characteristic of MS
Level Statistics of XXZ Spin Chains with Discrete Symmetries: Analysis through Finite-size Effects
Level statistics is discussed for XXZ spin chains with discrete symmetries
for some values of the next-nearest-neighbor (NNN) coupling parameter. We show
how the level statistics of the finite-size systems depends on the NNN coupling
and the XXZ anisotropy, which should reflect competition among quantum chaos,
integrability and finite-size effects. Here discrete symmetries play a central
role in our analysis. Evaluating the level-spacing distribution, the spectral
rigidity and the number variance, we confirm the correspondence between
non-integrability and Wigner behavior in the spectrum. We also show that
non-Wigner behavior appears due to mixed symmetries and finite-size effects in
some nonintegrable cases.Comment: 19 pages, 6 figure
Electronic States and Superconductivity in Multi-layer High-Tc Cuprates
We study electronic states of multilayer cuprates in the normal phases as
functions of the number of CuO_2 planes and the doping rate. The resonating
valence bond wave function and the Gutzwiller approximation are used for a
two-dimensional multilayer t-t'-t''-J model. We calculate the electron-removal
spectral functions at (\pi,0) in the CuO_2 plane next to the surface to
understand the angle-resolved photoemission spectroscopy (ARPES) spectra. We
find that the trilayer spectrum is narrower than the bilayer spectrum but is
wider than the monolayer spectrum. In the tri- and tetralayer systems, the
outer CuO_2 plane has different superconducting amplitude from the inner CuO_2
plane, while each layer in the bilayer systems has same amplitude. The recent
ARPES and NMR experiments are discussed in the light of the present theory.Comment: 7 pages, 7 figure
Charge Imbalance Effects on Interlayer Hopping and Fermi Surfaces in Multilayered High-T_c Cuprates
We study doping dependence of interlayer hoppings, t_\perp, in multilayered
cuprates with four or more CuO_2 planes in a unit cell. When the double
occupancy is forbidden in the plane, an effective amplitude of t_\perp in the
Gutzwiller approximation is shown to be proportional to the square root of the
product of doping rates in adjacent two planes, i.e., t^eff_\perp \propto
t_\perp \sqrt{\delta_1\delta_2}, where \delta_1 and \delta_2 represent the
doping rates of the two planes. More than three-layered cuprates have two kinds
of \cuo planes, i.e., inner- and outer planes (IP and OP), resulting in two
different values of t^eff_{\perp}, i.e., t^eff_\perp 1 \propto t_\perp
\sqrt{\delta_IP \delta_IP} between IP's, and t^eff_\perp 2 \propto t_\perp
\sqrt{\delta_IP \delta_OP} between IP and OP. Fermi surfaces are calculated in
the four-layered t-t'-t''-J model by the mean-field theory. The order
parameters, the renormalization factor of t_\perp, and the site-potential
making the charge imbalance between IP and OP are self-consistently determined
for several doping rates. We show the interlayer splitting of the Fermi
surfaces, which may be observed in the angle resolved photoemission
spectroscopy measurement.Comment: Some typographical errors are revised. Journal of Physical Society of
Japan, Vol.75, No.3, in pres
Feasibility tests of transmission x-ray photoelectron emission microscopy of wet samples
We performed feasibility tests of photoelectron emission spectromicroscopy of wet samples in the water window (285-532 eV) soft x-ray spectral region. Water was successfully confined in an ultrahigh vacuum compatible compartment with x-ray transparent sides. This water cell was placed in the MEPHISTO spectromicroscope in a transmission geometry, and complete x-ray absorption spectra of the water window region were acquired. We also show micrographs of test samples, mounted outside of the compartment, and imaged through the water. This technique can be used to study liquid chemistry and, at least to the micron level, the microstructure of wet samples. Possibilities include cells in water or buffer, proteins in solution, oils of tribological interest, liquid crystals, and other samples not presently accessible to the powerful x-ray photoelectron emission spectromicroscopy technique
ltl Synthesis Under Environment Specifications for Reachability and Safety Properties
In this paper, we study ltlf synthesis under environment specifications for arbitrary reachability and safety properties. We consider both kinds of properties for both agent tasks and environment specifications, providing a complete landscape of synthesis algorithms. For each case, we devise a specific algorithm (optimal wrt complexity of the problem) and prove its correctness. The algorithms combine common building blocks in different ways. While some cases are already studied in literature others are studied here for the first time
High Efficiency Colloidal Quantum Dot Infrared Light Emitting Diodes via Engineering at the Supra-Nanocrystalline Level
Colloidal quantum dot (CQD) light-emitting diodes (LEDs) deliver a compelling performance in the visible, yet infrared CQD LEDs underperform their visible-emitting counterparts, largely due to their low photoluminescence quantum efficiency. Here we employ a ternary blend of CQD thin film that comprises a binary host matrix that serves to electronically passivate as well as to cater for an efficient and balanced carrier supply to the emitting quantum dot species. In doing so, we report infrared PbS CQD LEDs with an external quantum efficiency of ~7.9% and a power conversion efficiency of ~9.3%, thanks to their very low density of trap states, on the order of 1014 cm−3, and very high photoluminescence quantum efficiency in electrically conductive quantum dot solids of more than 60%. When these blend devices operate as solar cells they deliver an open circuit voltage that approaches their radiative limit thanks to the synergistic effect of the reduced trap-state density and the density of state modification in the nanocomposite.Peer ReviewedPostprint (author's final draft
Outcomes and Risk Factors for Complications of Laser Ablation for Thyroid Nodules: A Multicenter Study on 1531 Patients
Image-guided laser ablation therapy (LAT) of benign thyroid nodules demonstrated favorable results in randomized trials with fixed modalities of treatment. The aim of this retrospective multicenter study was to assess the effectiveness, tolerability, and complications of LAT in a large consecutive series of patients from centers using this technique in their routine clinical activity
Climate change and freshwater zooplankton: what does it boil down to?
Recently, major advances in the climate–zooplankton interface have been made some of which appeared to receive much attention in a broader audience of ecologists as well. In contrast to the marine realm, however, we still lack a more holistic summary of recent knowledge in freshwater. We
discuss climate change-related variation in physical and biological attributes of lakes and running waters, high-order ecological functions, and subsequent alteration
in zooplankton abundance, phenology, distribution, body size, community structure, life history parameters, and behavior by focusing on community level responses. The adequacy of large-scale climatic indices in ecology has received considerable support and provided a framework for the interpretation of community and species level responses in freshwater zooplankton. Modeling perspectives deserve particular consideration, since this promising stream of
ecology is of particular applicability in climate change
research owing to the inherently predictive nature of
this field. In the future, ecologists should expand their
research on species beyond daphnids, should address
questions as to how different intrinsic and extrinsic
drivers interact, should move beyond correlative
approaches toward more mechanistic explanations,
and last but not least, should facilitate transfer of
biological data both across space and time
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