2,209 research outputs found
High-Resolution Simulations of Cosmic Microwave Background non-Gaussian Maps in Spherical Coordinates
We describe a new numerical algorithm to obtain high-resolution simulated
maps of the Cosmic Microwave Background (CMB), for a broad class of
non-Gaussian models. The kind of non-Gaussianity we account for is based on the
simple idea that the primordial gravitational potential is obtained by a
non-linear but local mapping from an underlying Gaussian random field, as
resulting from a variety of inflationary models. Our technique, which is based
on a direct realization of the potential in spherical coordinates and fully
accounts for the radiation transfer function, allows to simulate non-Gaussian
CMB maps down to the Planck resolution (), with
reasonable memory storage and computational time.Comment: 9 pages, 5 figures. Submitted to ApJ. A version with higher quality
figures is available at http://www.pd.infn.it/~liguori/content.htm
The pulsed electron deposition technique for biomedical applications: A review
The "pulsed electron deposition" (PED) technique, in which a solid target material is ablated by a fast, high-energy electron beam, was initially developed two decades ago for the deposition of thin films of metal oxides for photovoltaics, spintronics, memories, and superconductivity, and dielectric polymer layers. Recently, PED has been proposed for use in the biomedical field for the fabrication of hard and soft coatings. The first biomedical application was the deposition of low wear zirconium oxide coatings on the bearing components in total joint replacement. Since then, several works have reported the manufacturing and characterization of coatings of hydroxyapatite, calcium phosphate substituted (CaP), biogenic CaP, bioglass, and antibacterial coatings on both hard (metallic or ceramic) and soft (plastic or elastomeric) substrates. Due to the growing interest in PED, the current maturity of the technology and the low cost compared to other commonly used physical vapor deposition techniques, the purpose of this work was to review the principles of operation, the main applications, and the future perspectives of PED technology in medicine
Anyonic Realization of the Quantum Affine Lie Superalgebra U_q(A(M,N)^{(1)})
We give a realization of the quantum affine Lie superalgebras U_q(A(M,N))^(1)
in terms of anyons defined on a one or two-dimensional lattice, the deformation
parameter q being related to the statistical parameter of the anyons by q
= exp(i\pi\nu). The construction uses anyons contructed from usual fermionic
oscillators and deformed bosonic oscillators. As a byproduct, realization
deformed in any sector of the quantum superalgebras U_q(A(M,N)) is obtained.Comment: 14p LaTeX Document (should be run twice
Bioinformatics tools for marine biotechnology: A practical tutorial with a metagenomic approach
Background: Bioinformatics has pervaded all fields of biology and has become an indispensable tool for almost all research projects. Although teaching bioinformatics has been incorporated in all traditional life science curricula, practical hands-on experiences in tight combination with wet-lab experiments are needed to motivate students. Results: We present a tutorial that starts from a practical problem: finding novel enzymes from marine environments. First, we introduce the idea of metagenomics, a recent approach that extends biotechnology to non-culturable microbes. We presuppose that a probe for the screening of metagenomic cosmid library is needed. The students start from the chemical structure of the substrate that should be acted on by the novel enzyme and end with the sequence of the probe. To attain their goal, they discover databases such as BRENDA and programs such as BLAST and Clustal Omega. Students' answers to a satisfaction questionnaire show that a multistep tutorial integrated into a research wet-lab project is preferable to conventional lectures illustrating bioinformatics tools. Conclusion: Experimental biologists can better operate basic bioinformatics if a problem-solving approach is chosen
Observational constraints on patch inflation in noncommutative spacetime
We study constraints on a number of patch inflationary models in
noncommutative spacetime using a compilation of recent high-precision
observational data. In particular, the four-dimensional General Relativistic
(GR) case, the Randall-Sundrum (RS) and Gauss-Bonnet (GB) braneworld scenarios
are investigated by extending previous commutative analyses to the infrared
limit of a maximally symmetric realization of the stringy uncertainty
principle. The effect of spacetime noncommutativity modifies the standard
consistency relation between the tensor spectral index and the tensor-to-scalar
ratio. We perform likelihood analyses in terms of inflationary observables
using new consistency relations and confront them with large-field inflationary
models with potential V \propto \vp^p in two classes of noncommutative
scenarios. We find a number of interesting results: (i) the quartic potential
(p=4) is rescued from marginal rejection in the class 2 GR case, and (ii) steep
inflation driven by an exponential potential (p \to \infty) is allowed in the
class 1 RS case. Spacetime noncommutativity can lead to blue-tilted scalar and
tensor spectra even for monomial potentials, thus opening up a possibility to
explain the loss of power observed in the cosmic microwave background
anisotropies. We also explore patch inflation with a Dirac-Born-Infeld tachyon
field and explicitly show that the associated likelihood analysis is equivalent
to the one in the ordinary scalar field case by using horizon-flow parameters.
It turns out that tachyon inflation is compatible with observations in all
patch cosmologies even for large p.Comment: 16 pages, 11 figures; v2: updated references, minor corrections to
match the Phys. Rev. D versio
Feedback cooling of the normal modes of a massive electromechanical system to submillikelvin temperature
We apply a feedback cooling technique to simultaneously cool the three
electromechanical normal modes of the ton-scale resonant-bar gravitational wave
detector AURIGA. The measuring system is based on a dc Superconducting Quantum
Interference Device (SQUID) amplifier, and the feedback cooling is applied
electronically to the input circuit of the SQUID. Starting from a bath
temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the
coolest normal mode. The same technique, implemented in a dedicated experiment
at subkelvin bath temperature and with a quantum limited SQUID, could allow to
approach the quantum ground state of a kilogram-scale mechanical resonator.Comment: 4 pages, 4 figure
Gauge-Invariant Quasi-Free States on the Algebra of the Anyon Commutation Relations
Let and let , . For and from , we define a function to be equal to if , and to if . Let , () be operator-valued distributions such that is the adjoint of . We say that , satisfy the anyon commutation relations (ACR) if for and for . In particular, for , the ACR become the canonical commutation relations and for , the ACR become the canonical anticommutation relations. We define the ACR algebra as the algebra generated by operator-valued integrals of , . We construct a class of gauge-invariant quasi-free states on the ACR algebra. Each state from this class is completely determined by a positive self-adjoint operator on the real space which commutes with any operator of multiplication by a bounded function . In the case ), we discuss the corresponding particle density . For , using a renormalization, we rigorously define a vacuum state on the commutative algebra generated by operator-valued integrals of . This state is given by a negative binomial point process. A scaling limit of these states as gives the gamma random measure, depending on parameter
Pharmacological chaperones: A therapeutic approach for diseases caused by destabilizing missense mutations
The term “pharmacological chaperone” was introduced 20 years ago. Since then the approach with this type of drug has been proposed for several diseases, lysosomal storage disorders representing the most popular targets. The hallmark of a pharmacological chaperone is its ability to bind a protein specifically and stabilize it. This property can be beneficial for curing diseases that are associated with protein mutants that are intrinsically active but unstable. The total activity of the affected proteins in the cell is lower than normal because they are cleared by the quality control system. Although most pharmacological chaperones are reversible competitive inhibitors or antagonists of their target proteins, the inhibitory activity is neither required nor desirable. This issue is well documented by specific examples among which those concerning Fabry disease. Direct specific binding is not the only mechanism by which small molecules can rescue mutant proteins in the cell. These drugs and the properly defined pharmacological chaperones can work together with different and possibly synergistic modes of action to revert a disease phenotype caused by an unstable protein
Neural Surface Antibodies and Neurodegeneration: Clinical Commonalities and Pathophysiological Relationships
Autoimmune encephalitis and neurodegenerative disorders share several clinical features, including behavioural and psychiatric manifestations, cognitive impairment, sleep and movement disorders. Therefore, it is not surprising that autoimmune encephalitis is one of the main differential diagnoses of rapidly progressive dementia. However, more chronic presentations of autoimmune disorders have been reported and can lead to the misdiagnosis of a neurodegenerative disease. On the other hand, antibodies against neuronal proteins, such as those directed against NMDAR, can occur during established neurogenerative disorders, and their role in this context is still unclear. They might be simple bystanders or modify the disease course and phenotype. Indeed, autoimmune encephalitis can leave long-term cognitive sequelae and specific antibodies to neuronal surface antigens are associated with clinical and pathological neurodegenerative features. Here we review the link between these antibodies and neurodegeneration. In particular we discuss: (a) the possibility that autoimmune encephalitis presents as a neurodegenerative disease, identifying the red flags that can help in the differential diagnosis between antibody-mediated and neurodegenerative disorders; (b) the occurrence of antibodies against neuronal surface antigens in patients with neurodegenerative disorders and their possible role in the disease course; and (c) the long-term cognitive and neuroradiological changes associated with autoimmune encephalitis, as well as the biomarkers that can help to predict the cognitive outcome. Finally, we review the clinical and pathological features of IgLON5 antibodies-related encephalitis, a unique model of the relationship between antibodies and neurodegeneration
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