11,893 research outputs found
SiC(0001): a surface Mott-Hubbard insulator
We present ab-initio electronic structure calculations for the Si-terminated
SiC(0001) surface. While local density approximation
(LDA) calculations predict a metallic ground state with a half-filled narrow
band, Coulomb effects, included by the spin-polarized LDA+U method, result in a
magnetic (Mott-Hubbard) insulator with a gap of 1.5 eV, comparable with the
experimental value of 2.0 eV. The calculated value of the inter-site exchange
parameter, J=30K, leads to the prediction of a paramagnetic Mott state, except
at very low temperatures. The observed Si 2p surface core level doublet can
naturally be explained as an on-site exchange splitting.Comment: RevTex, 4 pages, 4 eps-figure
Retroperitoneal fibrosis: a case of a patient (63y/o) treated with low-dose methotrexate (MTX) and 6-methylprednisolone (6-MP)
Retroperitoneal fibrosis (RPF), is a rare fibroinflammatory disease. The pathogenesis of RPF is still unclear and numerous theories have
been reported such as environmental factors, immunologic process, genetic component, local inflammation and advanced atherosclerosis.
RPF is characterized by the presence of a particular retroperitoneal fibrotic tissue which is white, woody and involving retroperitoneal
structures such as the great vessels, ureters and psoas muscle. The main complication of RPF is the obstruction of local structures such as
the ureters due to the fibrosis and the treatment of this aspect represents the main challenge for this pathology.
RPF medical treatment consists of corticosteroids or/and immunosuppressive therapy. We report a case of a patient (63y/o) affected by
idiopathic RPF treated with low-dose methotrexate (MTX) and 6-methylprednisolone (6-MP) for two years, describing and confirming the
effectiveness and safety of a long-term low-dose MTX and 6-MP treatment
Population status of the Oblong turtle in Armadale’s wetlands
The Oblong turtle (Chelodina oblonga) is becoming a flagship species for Perth wetlands. As an apex predator the species plays an essential role in wetland ecosystem health. However, urban populations appear to be in decline due to numerous threats including habitat modification and destruction, wildlife-vehicle mortality, and predation. Three wetlands within City of Armadale were identified by the Armadale Gosnells Landcare Group as potentially significant sites for populations of the Oblong turtle. No baseline information on the presence and/or population status of C. oblonga within these wetlands currently exists. Modified funnel traps and fyke nets were deployed for an overnight trapping period in each wetland during October 2020. In total, thirty-four turtles were captured and released from the wetlands. The turtles captured were mainly adults and the few juveniles captured were >100 mm. Sex ratio varied from heavily male-dominated to slightly female-dominated. The results suggest that these populations have been experiencing low recruitment, and sex biased mortality at the heavily male dominated population. Continued monitoring of these populations as well as expansion of surveys to additional wetlands will enable a deeper understanding of C. oblonga population dynamics within the City of Armadale, as well as wetland-specific management recommendations
Splenomegaly impacts prognosis in essential thrombocythemia and polycythemia vera: A single center study
Splenomegaly is one of the major clinical manifestations of primary myelofibrosis and is common also in other chronic Philadelphia-negative myeloproliferative neoplasms, causing symptoms and signs and affecting quality of life of patients diagnosed with these diseases. We aimed to study the impact that such alteration has on thrombotic risk and on the survival of patients with essential thrombocythemia and patients with Polycythemia Vera (PV). We studied the relationship between splenomegaly (and its grade), thrombosis and survival in 238 patients with et and 165 patients with PV followed at our center between January 1997 and May 2019
KCa3.1 inhibition switches the phenotype of glioma-infiltrating microglia/macrophages
Among the strategies adopted by glioma to successfully invade the brain parenchyma is turning the infiltrating microglia/macrophages (M/MΦ) into allies, by shifting them toward an anti-inflammatory, pro-tumor phenotype. Both glioma and infiltrating M/MΦ cells express the Ca(2+)-activated K(+) channel (KCa3.1), and the inhibition of KCa3.1 activity on glioma cells reduces tumor infiltration in the healthy brain parenchyma. We wondered whether KCa3.1 inhibition could prevent the acquisition of a pro-tumor phenotype by M/MΦ cells, thus contributing to reduce glioma development. With this aim, we studied microglia cultured in glioma-conditioned medium or treated with IL-4, as well as M/MΦ cells acutely isolated from glioma-bearing mice and from human glioma biopsies. Under these different conditions, M/MΦ were always polarized toward an anti-inflammatory state, and preventing KCa3.1 activation by 1-[(2-Chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34), we observed a switch toward a pro-inflammatory, antitumor phenotype. We identified FAK and PI3K/AKT as the molecular mechanisms involved in this phenotype switch, activated in sequence after KCa3.1. Anti-inflammatory M/MΦ have higher expression levels of KCa3.1 mRNA (kcnn4) that are reduced by KCa3.1 inhibition. In line with these findings, TRAM-34 treatment, in vivo, significantly reduced the size of tumors in glioma-bearing mice. Our data indicate that KCa3.1 channels are involved in the inhibitory effects exerted by the glioma microenvironment on infiltrating M/MΦ, suggesting a possible role as therapeutic targets in glioma
Radiological and surgical aspects of polymorphous low-grade neuroepithelial tumor of the young (PLNTY)
Background: Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a low-grade epilepsy-associated tumor recently introduced in WHO 2021 classification. Since it has been recognized as an independent nosological entity, PLNTY has been mainly studied from a genetic and molecular perspective, not recognizing unique characteristic clinical and radiological features. Methods: A systematic literature research has been conducted aiming to identify all relevant studies about the radiological, clinical and surgical features of PLNTY. We described a representative case of a 45-year-old man treated with awake-surgery with confirmed diagnosis of PLNTY, reporting the radiological and surgical characteristics through imaging and intra-operative video. We performed a statistical meta-analysis attempting to assess the presence of relationships between surgical and radiologic tumor characteristics and clinical outcome and type of surgery. Results: A total of 16 studies were included in the systematic review. The final cohort was composed of 51 patients. Extent of resection (EOR) and outcome are not significantly associated with the different genetic profiling (p = 1), the presence of cystic intralesional component, calcification (p = 0.85), contrast-enhancing and lesion boundaries (p = 0.82). No significant correlation there is between EOR and remission or better control of epilepsy-related symptoms (p = 0.38). The contrast enhancement in the tumor is significantly associated with recurrence or poor control of epileptic symptoms (p = 0.07). Conclusions: In PLNTYs, contrast enhancement seems to impact prognosis, recurrence, and seizure control much more than radiological features, genetic features and type of resection of the tumor
Speeding up critical system dynamics through optimized evolution
The number of defects which are generated on crossing a quantum phase
transition can be minimized by choosing properly designed time-dependent
pulses. In this work we determine what are the ultimate limits of this
optimization. We discuss under which conditions the production of defects
across the phase transition is vanishing small. Furthermore we show that the
minimum time required to enter this regime is , where
is the minimum spectral gap, unveiling an intimate connection between
an optimized unitary dynamics and the intrinsic measure of the Hilbert space
for pure states. Surprisingly, the dynamics is non-adiabatic, this result can
be understood by assuming a simple two-level dynamics for the many-body system.
Finally we classify the possible dynamical regimes in terms of the action
.Comment: 6 pages, 6 figure
MESENCHYMAL STEM CELLS IN PH-NEGATIVE MYELOPROLIFERATIVE NEOPLASMS: IDLE OBSERVERS OR PART OF THE DISEASE?
Complexity-Entropy Causality Plane as a Complexity Measure for Two-dimensional Patterns
Complexity measures are essential to understand complex systems and there are
numerous definitions to analyze one-dimensional data. However, extensions of
these approaches to two or higher-dimensional data, such as images, are much
less common. Here, we reduce this gap by applying the ideas of the permutation
entropy combined with a relative entropic index. We build up a numerical
procedure that can be easily implemented to evaluate the complexity of two or
higher-dimensional patterns. We work out this method in different scenarios
where numerical experiments and empirical data were taken into account.
Specifically, we have applied the method to i) fractal landscapes generated
numerically where we compare our measures with the Hurst exponent; ii) liquid
crystal textures where nematic-isotropic-nematic phase transitions were
properly identified; iii) 12 characteristic textures of liquid crystals where
the different values show that the method can distinguish different phases; iv)
and Ising surfaces where our method identified the critical temperature and
also proved to be stable.Comment: Accepted for publication in PLoS On
Click-based porous cationic polymers for enhanced carbon dioxide capture
Imidazolium based porous cationic polymers were synthesized using an
innovative and facile approach, which takes advantage of the Debus Radziszewski
reaction to obtain meso- and microporous polymers following click chemistry
principles. In the obtained set of materials, click based porous cationic
polymers have the same cationic backbone, whereas they bear the commonly used
anions of imidazolium poly(ionic liquid)s. These materials show hierarchical
porosity and a good specific surface area. Furthermore, their chemical
structure was extensively characterized using ATR FTIR and SS NMR
spectroscopies, and HR MS. These polymers show good performance towards carbon
dioxide sorption, especially those possessing the acetate anion. This polymer
has an uptake of 2 mmol per g of CO2 at 1 bar and 273 K, a value which is among
the highest recorded for imidazolium poly(ionic liquid)s. These polymers were
also modified in order to introduce N-heterocyclic carbenes along the backbone.
Carbon dioxide loading in the carbene-containing polymer is in the same range
as that of the non-modified versions, but the nature of the interaction is
substantially different. The combined use of in situ FTIR spectroscopy and
microcalorimetry evidenced a chemisorption phenomenon that brings about the
formation of an imidazolium carboxylate zwitterion.Comment: 29 page, 33 figure
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