14,769 research outputs found
p38α (MAPK14) critically regulates the immunological response and the production of specific cytokines and chemokines in astrocytes.
In CNS lesions, "reactive astrocytes" form a prominent cellular response. However, the nature of this astrocyte immune activity is not well understood. In order to study astrocytic immune responses to inflammation and injury, we generated mice with conditional deletion of p38α (MAPK14) in GFAP+ astrocytes. We studied the role of p38α signaling in astrocyte immune activation both in vitro and in vivo, and simultaneously examined the effects of astrocyte activation in CNS inflammation. Our results showed that specific subsets of cytokines (TNFα, IL-6) and chemokines (CCL2, CCL4, CXCL1, CXCL2, CXCL10) are critically regulated by p38α signaling in astrocytes. In an in vivo CNS inflammation model of intracerebral injection of LPS, we observed markedly attenuated astrogliosis in conditional GFAPcre p38α(-/-) mice. However, GFAPcre p38α(-/-) mice showed marked upregulation of CCL2, CCL3, CCL4, CXCL2, CXCL10, TNFα, and IL-1β compared to p38αfl/fl cohorts, suggesting that in vivo responses to LPS after GFAPcre p38α deletion are complex and involve interactions between multiple cell types. This finding was supported by a prominent increase in macrophage/microglia and neutrophil recruitment in GFAPcre p38α(-/-) mice compared to p38αfl/fl controls. Together, these studies provide important insights into the critical role of p38α signaling in astrocyte immune activation
Semistable Higgs bundles on Calabi-Yau manifolds
We provide a partial classification of semistable Higgs bundles over a simply connected Calabi-Yau manifolds. Applications to a conjecture about a special class of semistable Higgs bundles are given. In particular, the conjecture is proved for K3 and Enriques surfaces, and some related classes of surfaces
Critical assessment of two-qubit post-Markovian master equations
A post-Markovian master equation has been recently proposed as a tool to
describe the evolution of a system coupled to a memory-keeping environment [A.
Shabani and D. A. Lidar, Phys. Rev. A 71, 020101 (R) (2005)]. For a single
qubit affected by appropriately chosen environmental conditions, the
corresponding dynamics is always legitimate and physical. Here we extend such
situation to the case of two qubits, only one of which experiences the
environmental effects. We show how, despite the innocence of such an extension,
the introduction of the second qubit should be done cum grano salis to avoid
consequences such as the breaking of the positivity of the associated dynamical
map. This hints at the necessity of using care when adopting phenomenologically
derived models for evolutions occurring outside the Markovian framework.Comment: 7 pages, 1 figure, RevTeX4. Close to published versio
Sharing economy and dynamic pricing: Is the impact of Airbnb on the hotel industry time-dependent?
Prior literature has reported significant price and revenue reductions in the hotel industry due to the emergence of Airbnb. Other studies have documented that hotels' price reactions to the penetration of Airbnb depend on their service level, e.g., low/medium-end versus high end. Relying on a large sample from the Italian market, we contribute by showing that the effect of Airbnb on hotels' price decisions does not only depend on incumbents’ quality level, but also on the difference between booking and check-in time. That is, the effect of the penetration of Airbnb on hotels' dynamic price decisions varies over time depending on the core segment hotels target
Virtual reality for the analysis and visualization of scientific numerical models
The complexity of the data generated by (magneto)-hydrodynamic (HD/MHD)
simulations requires advanced tools for their analysis and visualization. The
dramatic improvements in virtual reality (VR) technologies have inspired us to
seek the long-term goal of creating VR tools for scientific model analysis and
visualization that would allow researchers to study and perform data analysis
on their models within an immersive environment. Here, we report the results
obtained at INAF-Osservatorio Astronomico di Palermo in the development of
these tools, which would allow for the exploration of 3D models interactively,
resulting in highly detailed analysis that cannot be performed with traditional
data visualization and analysis platforms. Additionally, these VR-based tools
offer the ability to produce high-impact VR content for efficient audience
engagement and awareness.Comment: 9 pages, 5 figures, proceedings of the conference "Virtual and
augmented reality for public outreach". Accepted for publication on Mem. SAI
Active shape correction of a thin glass/plastic X-ray mirror
Optics for future X-ray telescopes will be characterized by very large
aperture and focal length, and will be made of lightweight materials like glass
or plastic in order to keep the total mass within acceptable limits. Optics
based on thin slumped glass foils are currently in use in the NuSTAR telescope
and are being developed at various institutes like INAF/OAB, aiming at
improving the angular resolution to a few arcsec HEW. Another possibility would
be the use of thin plastic foils, being developed at SAO and the Palermo
University. Even if relevant progresses in the achieved angular resolution were
recently made, a viable possibility to further improve the mirror figure would
be the application of piezoelectric actuators onto the non-optical side of the
mirrors. In fact, thin mirrors are prone to deform, so they require a careful
integration to avoid deformations and even correct forming errors. This however
offers the possibility to actively correct the residual deformation. Even if
other groups are already at work on this idea, we are pursuing the concept of
active integration of thin glass or plastic foils with piezoelectric patches,
fed by voltages driven by the feedback provided by X-rays, in intra-focal setup
at the XACT facility at INAF/OAPA. In this work, we show the preliminary
simulations and the first steps taken in this project
Invited response on: dual-plane retro-pectoral versus pre-pectoral dti breast reconstruction. An italian multicenter experience
Invited Response on: Dual-Plane Retro-Pectoral Versus Pre-pectoral DTI Breast Reconstruction: An Italian Multicenter Experienc
Spin-one ferromagnets with single-ion anisotropy in a perpendicular external field
In this paper, the conventional Holstein-Primakoff method is generalized with
the help of the characteristic angle transformation [Lei Zhou and Ruibao Tao,
J. Phys. A {\bf 27} 5599 (1994)] for the spin-one magnetic systems with
single-ion anisotropies. We find that the weakness of the conventional method
for such systems can be overcome by the new approach. Two models will be
discussed to illuminate the main idea, which are the ``easy-plane" and the
``easy-axis" spin-one ferromagnet, respectively. Comparisons show that the
current approach can give reasonable ground state properties for the magnetic
system with ``easy-plane" anisotropy though the conventional method never can,
and can give a better representation than the conventional one for the magnetic
system with ``easy-axis" anisotropy though the latter is usually believed to be
a good approximation in such case. Study of the easy-plane model shows that
there is a phase transition induced by the external field, and the
low-temperature specific heat may have a peak as the field reaches the critical
value.Comment: Using LaTex. To be published in the September 1 issue of Physical
Review B (1996). Email address: [email protected]
Cell organization in soft media due to active mechanosensing
Adhering cells actively probe the mechanical properties of their environment
and use the resulting information to position and orient themselves. We show
that a large body of experimental observations can be consistently explained
from one unifying principle, namely that cells strengthen contacts and
cytoskeleton in the direction of large effective stiffness. Using linear
elasticity theory to model the extracellular environment, we calculate optimal
cell organization for several situations of interest and find excellent
agreement with experiments for fibroblasts, both on elastic substrates and in
collagen gels: cells orient in the direction of external tensile strain, they
orient parallel and normal to free and clamped surfaces, respectively, and they
interact elastically to form strings. Our method can be applied for rational
design of tissue equivalents. Moreover our results indicate that the concept of
contact guidance has to be reevaluated. We also suggest that cell-matrix
contacts are upregulated by large effective stiffness in the environment
because in this way, build-up of force is more efficient.Comment: Revtex, 7 pages, 4 Postscript files include
Why Librarianship? A Comparative Study Between University of Tsukuba, University of Hong Kong, University of British Columbia and Shanghai University
Career decisions are motivated in part by our internal values, but also are influenced strongly by innumerable external forces perceived in the context of our lives. In the research reported here, we explore various social, cultural, economic, and educational factors, as well as personal and professional reasons that influence students in choosing library and information science professions as a career. Master of Library and Information Science (MLIS) students from four universities located in four different regions were invited to take part in an online questionnaire survey. The universities were Shanghai University (SHU), the University of British Columbia (UBC), the University of Hong Kong (HKU) and the University of Tsukuba (UT). 175 self-completed questionnaires were collected in total. Survey results indicated that students enrolled in MLIS programmes were predominately female. Differences and similarities were encountered for the different sites. For example HKU and UBC had the largest number of students with graduate-level qualifications prior to entering the MLIS programme and students at HKU and UBC tended to vary widely in terms of their educational and occupational backgrounds. For the majority of the HKU and UBC respondents, the decision to obtain a professional qualification in LIS was driven by the desire to maximize the benefits of a career change or for career advancement, while the majority of respondents at the UT and SHU did not already have a job or much working experience. While the total surveyed populations are small; the study will be of interest and value to LIS educators and administrators responsible for recruiting MLIS graduates and hiring LIS professions.postprin
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