1,771 research outputs found
The Kibble-Zurek Problem: Universality and the Scaling Limit
Near a critical point, the equilibrium relaxation time of a system diverges
and any change of control/thermodynamic parameters leads to non-equilibrium
behavior. The Kibble-Zurek problem is to determine the dynamical evolution of
the system parametrically close to its critical point when the change is
parametrically slow. The non-equilibrium behavior in this limit is controlled
entirely by the critical point and the details of the trajectory of the system
in parameter space (the protocol) close to the critical point. Together, they
define a universality class consisting of critical exponents-discussed in the
seminal work by Kibble and Zurek-and scaling functions for physical quantities,
which have not been discussed hitherto. In this article, we give an extended
and pedagogical discussion of the universal content in the Kibble-Zurek
problem. We formally define a scaling limit for physical quantities near
classical and quantum transitions for different sets of protocols. We report
computations of a few scaling functions in model Gaussian and large-N problems
and prove their universality with respect to protocol choice. We also introduce
a new protocol in which the critical point is approached asymptotically at late
times with the system marginally out of equilibrium, wherein logarithmic
violations to scaling and anomalous dimensions occur even in the simple
Gaussian problem.Comment: 19 pages,10 figure
Boxicity of graphs on surfaces
The boxicity of a graph is the least integer for which there
exist interval graphs , , such that . Scheinerman proved in 1984 that outerplanar graphs have boxicity
at most two and Thomassen proved in 1986 that planar graphs have boxicity at
most three. In this note we prove that the boxicity of toroidal graphs is at
most 7, and that the boxicity of graphs embeddable in a surface of
genus is at most . This result yields improved bounds on the
dimension of the adjacency poset of graphs on surfaces.Comment: 9 pages, 2 figure
Landowner Characteristics Associated with Receiving Information About Invasive Plants and Implications for Outreach Providers
Based on a survey of woodland owners in West Virginia, we examined the possibility of differences in the characteristics of those who had and had not received information about local invasive plants and implications for outreach providers. Findings suggest that landowners who farmed on their property, held recreation objectives, and lived in the local area were significantly more likely than their counterparts to have received information. A majority of landowners with these characteristics, however, had not heard or read such information. Implications for expanding awareness through both traditional and non-traditional information channels are presented
Passively Administered Pooled Human Immunoglobulins Exert IL-10 Dependent Anti-Inflammatory Effects that Protect against Fatal HSV Encephalitis
HSV-1 is the leading cause of sporadic encephalitis in humans. HSV infection of susceptible 129S6 mice results in fatal encephalitis (HSE) caused by massive inflammatory brainstem lesions comprising monocytes and neutrophils. During infection with pathogenic microorganisms or autoimmune disease, IgGs induce proinflammatory responses and recruit innate effector cells. In contrast, high dose intravenous immunoglobulins (IVIG) are an effective treatment for various autoimmune and inflammatory diseases because of potent anti-inflammatory effects stemming in part from sialylated IgGs (sIgG) present at 1â3% in IVIG. We investigated the ability of IVIG to prevent fatal HSE when given 24 h post infection. We discovered a novel anti-inflammatory pathway mediated by low-dose IVIG that protected 129S6 mice from fatal HSE by modulating CNS inflammation independently of HSV specific antibodies or sIgG. IVIG suppressed CNS infiltration by pathogenic CD11b+ Ly6Chigh monocytes and inhibited their spontaneous degranulation in vitro. FcÎłRIIb expression was required for IVIG mediated suppression of CNS infiltration by CD45+ Ly6Clow monocytes but not for inhibiting development of Ly6Chigh monocytes. IVIG increased accumulation of T cells in the CNS, and the non-sIgG fraction induced a dramatic expansion of FoxP3+ CD4+ T regulatory cells (Tregs) and FoxP3â ICOS+ CD4+ T cells in peripheral lymphoid organs. Tregs purified from HSV infected IVIG treated, but not control, mice protected adoptively transferred mice from fatal HSE. IL-10, produced by the ICOS+ CD4+ T cells that accumulated in the CNS of IVIG treated, but not control mice, was essential for induction of protective anti-inflammatory responses. Our results significantly enhance understanding of IVIG's anti-inflammatory and immunomodulatory capabilities by revealing a novel sIgG independent anti-inflammatory pathway responsible for induction of regulatory T cells that secrete the immunosuppressive cytokine IL-10 and further reveal the therapeutic potential of IVIG for treating viral induced inflammatory diseases
Electrooxidation of nitrite ions on gold/polyaniline/carbon paste electrode
Nitrite ions can penetrate from fertilizers into underground water and consequently contaminate the water and food sources. A facile two-step electrochemical method was used to fabricate gold/polyaniline/carbon paste electrode (Au/PAni/CPE) for nitrite sensing. The Au/PAni/CPE was visualized and characterized by scanning electron microscopy, energy-dispersed X-ray spectroscopy, X-ray diffraction and electrochemical methods. The electrocatalytic activity of bare CPE, PAni/CPE and Au/PAni/CPE toward the electrooxidation of nitrite was examined and compared via cyclic voltammetry. To obtain the optimal condition for fabrication of the electrode, the number of cycles in cyclic voltammetry for synthesis of polyaniline and the deposition time in potentiostatic deposition of gold were optimized with respect to the electrooxidation of nitrite. In a phosphate buffer solution (PBS, pH 7.0), the peak current was linear to the concentration of nitrite in the range from 3.8Ă10-5 M to 1.0Ă10-3 M with a detection limit of 2.5Ă10-5 M. The interference effect on the nitrite detection was also studied. The proposed method was also employed for the determination of nitrite in rain and lake water samples
Meteorite impact craters as hotspots for mineral resources and energy fuels: A global review
The ever-increasing recovery rate of natural resources from terrestrial impact craters over the last few decades across the globe offers new avenues for further exploration of mineral and hydrocarbon resources in such settings. As of today, 60 of the 208 terrestrial craters have been identified to host diverse resources such as hydrocarbons, metals and construction materials. The potential of craters as plausible resource contributors to the energy sector is therefore, worthy of consideration, as 42 (70%) of the 60 craters host energy resources such as oil, gas, coal, uranium, mercury, critical and major minerals as well as hydropower resources. Among others, 19 craters are of well-developed hydrocarbon reserves. Mineral deposits associated with craters are also classified similar to other mineral resources such as progenetic, syngenetic and epigenetic sources. Of these, the progenetic and syngenetic mineralization are confined to the early and late excavation stage of impact crater evolution, respectively, whereas epigenetic deposits are formed during and after the modification stage of crater formation. Thus, progenetic and syngenetic mineral deposits (like Fe, Ni, Pb, Zn and Cu) associated with craters are formed as a direct result of the impact event, whereas epigenetic deposits (e.g. hydrocarbon) are hosted by the impact structure and result from post-impact processes. In the progenetic and syngenetic deposits, the shock-wave induced fracturing and melting aid the formation of deposits, whereas in the epigenetic deposits, the highly fractured lithostratigraphic units of higher porosity and permeability, like the central elevated area (CEA) or the rim, act as traps. In this review, we provide a holistic view of the mineral and energy resources associated with impact craters, and use some of the remote sensing techniques to identify the mineral deposits as supplemented by a schematic model of the types of deposits formed during cratering process
Usporedna analiza sekvenci dijagnostiÄkih PCR umnoĆŸaka virusa ovÄjih boginja iz indijske ovce
Field samples were identified by agar gel precipitation and polymerase chain reaction (PCR) as positive for sheeppox virus. Envelope protein gene PCR amplicons (192 bp) of Indian sheeppox viruses isolated in 1997 and 2003 were sequenced to analyse nucleotide divergence. Analysis revealed that 2003 isolates possessed 100% nucleotide identity to each other, but only 95% nucleotide and amino acid were identity to an isolate from 1997. These Indian isolates were unique from other capripox virus sequences in that they contained a single codon insertion. Consistent with previous findings, the results indicate that recent sheepox virus isolates in India are more similar to previously described sheepox virus than to goatpox viruses from India and elsewhere.Virus ovÄjih boginja dokazan je u terenskim uzorcima imunodifuzijom u gelu i lanÄanom reakcijom polimeraze (PCR). PCR umnoĆĄci gena za protein ovojnice (192 pb) indijskih izolata virusa ovÄjih boginja izdvojenih tijekom 1997. i 2003. razlikovali su se po nukleotidnom slijedu. Izolati iz 2003. meÄusobno su bili identiÄni u 100% nukleotida, dok je izolat iz 1997. bio njima podudaran samo u 95% nukleotida i aminokiselina. Ti indijski izolati bili su jedinstveni u odnosu na druge viruse boginja koza po jednom ugraÄenom kodonu. U skladu s prijaĆĄnjim istraĆŸivanjima, nalazi ukazuju da su nedavni izolati virusa ovÄjih boginja u Indiji sliÄniji ranije opisanim virusima ovÄjih boginja nego virusima kozjih boginja iz Indije i drugdje
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