160 research outputs found
Google matrix of business process management
Development of efficient business process models and determination of their
characteristic properties are subject of intense interdisciplinary research.
Here, we consider a business process model as a directed graph. Its nodes
correspond to the units identified by the modeler and the link direction
indicates the causal dependencies between units. It is of primary interest to
obtain the stationary flow on such a directed graph, which corresponds to the
steady-state of a firm during the business process. Following the ideas
developed recently for the World Wide Web, we construct the Google matrix for
our business process model and analyze its spectral properties. The importance
of nodes is characterized by Page-Rank and recently proposed CheiRank and
2DRank, respectively. The results show that this two-dimensional ranking gives
a significant information about the influence and communication properties of
business model units. We argue that the Google matrix method, described here,
provides a new efficient tool helping companies to make their decisions on how
to evolve in the exceedingly dynamic global market.Comment: submitted to European Journal of Physics
Using the Hadamard and related transforms for simplifying the spectrum of the quantum baker's map
We rationalize the somewhat surprising efficacy of the Hadamard transform in
simplifying the eigenstates of the quantum baker's map, a paradigmatic model of
quantum chaos. This allows us to construct closely related, but new, transforms
that do significantly better, thus nearly solving for many states of the
quantum baker's map. These new transforms, which combine the standard Fourier
and Hadamard transforms in an interesting manner, are constructed from
eigenvectors of the shift permutation operator that are also simultaneous
eigenvectors of bit-flip (parity) and possess bit-reversal (time-reversal)
symmetry.Comment: Version to appear in J. Phys. A. Added discussions; modified title;
corrected minor error
Time evolution of Wikipedia network ranking
We study the time evolution of ranking and spectral properties of the Google
matrix of English Wikipedia hyperlink network during years 2003 - 2011. The
statistical properties of ranking of Wikipedia articles via PageRank and
CheiRank probabilities, as well as the matrix spectrum, are shown to be
stabilized for 2007 - 2011. A special emphasis is done on ranking of Wikipedia
personalities and universities. We show that PageRank selection is dominated by
politicians while 2DRank, which combines PageRank and CheiRank, gives more
accent on personalities of arts. The Wikipedia PageRank of universities
recovers 80 percents of top universities of Shanghai ranking during the
considered time period.Comment: 10 pages, 11 figures. Accepted for publication in EPJ
Hypersensitivity and chaos signatures in the quantum baker's maps
Classical chaotic systems are distinguished by their sensitive dependence on
initial conditions. The absence of this property in quantum systems has lead to
a number of proposals for perturbation-based characterizations of quantum
chaos, including linear growth of entropy, exponential decay of fidelity, and
hypersensitivity to perturbation. All of these accurately predict chaos in the
classical limit, but it is not clear that they behave the same far from the
classical realm. We investigate the dynamics of a family of quantizations of
the baker's map, which range from a highly entangling unitary transformation to
an essentially trivial shift map. Linear entropy growth and fidelity decay are
exhibited by this entire family of maps, but hypersensitivity distinguishes
between the simple dynamics of the trivial shift map and the more complicated
dynamics of the other quantizations. This conclusion is supported by an
analytical argument for short times and numerical evidence at later times.Comment: 32 pages, 6 figure
An inflammation-targeting hydrogel for local drug delivery in inflammatory bowel disease
There is a clinical need for new, more effective treatments for chronic and debilitating inflammatory bowel disease (IBD), including Crohnâs disease and ulcerative colitis. Targeting drugs selectively to the inflamed intestine may improve therapeutic outcomes and minimize systemic toxicity. We report the development of an inflammation-targeting hydrogel (IT-hydrogel) that acts as a drug delivery system to the inflamed colon. Hydrogel microfibers were generated from ascorbyl palmitate, an amphiphile that is generally recognized as safe (GRAS) by the U.S. Food and Drug Administration. IT-hydrogel microfibers loaded with the anti-inflammatory corticosteroid dexamethasone (Dex) were stable, released drug only upon enzymatic digestion, and demonstrated preferential adhesion to inflamed epithelial surfaces in vitro and in two mouse colitis models in vivo. Dex-loaded IT-hydrogel enemas, but not free Dex enemas, administered every other day to mice with colitis resulted in a significant reduction in inflammation and were associated with lower Dex peak serum concentrations and, thus, less systemic drug exposure. Ex vivo analysis of colon tissue samples from patients with ulcerative colitis demonstrated that IT-hydrogel microfibers adhered preferentially to mucosa from inflamed lesions compared with histologically normal sites. The IT-hydrogel drug delivery platform represents a promising approach for targeted enema-based therapies in patients with colonic IBD
Plasma neurofilament light as a potential biomarker of neurodegeneration in Alzheimerâs disease
BACKGROUND: A growing body of evidence suggests that the plasma concentration of the neurofilament light chain (NfL) might be considered a plasma biomarker for the screening of neurodegeneration in Alzheimerâs disease (AD). METHODS: With a single molecule array method (Simoa, Quanterix), plasma NfL concentrations were measured in 99 subjects with AD at the stage of mild cognitive impairment (MCI-AD; nâ=â25) or at the stage of early dementia (ADD; nâ=â33), and in nondemented controls (nâ=â41); in all patients, the clinical diagnoses were in accordance with the results of the four core cerebrospinal fluid (CSF) biomarkers (amyloid ÎČ (AÎČ)1â42, AÎČ42/40, Tau, and pTau181), interpreted according to the Erlangen Score algorithm. The influence of preanalytical storage procedures on the NfL in plasma was tested on samples exposed to six different conditions. RESULTS: NfL concentrations significantly increased in the samples exposed to more than one freezing/thawing cycle, and in those stored for 5 days at room temperature or at 4 °C. Compared with the control group of nondemented subjects (22.0â±â12.4 pg/mL), the unadjusted plasma NfL concentration was highly significantly higher in the MCI-AD group (38.1â±â15.9 pg/mL, pâ<â0.005) and even further elevated in the ADD group (49.1â±â28.4 pg/mL; pâ<â0.001). A significant association between NfL and age (Ïâ=â0.65, pâ<â0.001) was observed; after correcting for age, the difference in NfL concentrations between AD and controls remained significant (pâ=â0.044). At the cutoff value of 25.7 pg/mL, unconditional sensitivity, specificity, and accuracy were 0.84, 0.78, and 0.82, respectively. Unadjusted correlation between plasma NfL and Mini Mental State Examination (MMSE) across all patients was moderate but significant (râ=ââ0.49, pâ<â0.001). We observed an overall significant correlation between plasma NfL and the CSF biomarkers, but this correlation was not observed within the diagnostic groups. CONCLUSIONS: This study confirms increased concentrations of plasma NfL in patients with Alzheimerâs disease compared with nondemented controls
Quantum walks: a comprehensive review
Quantum walks, the quantum mechanical counterpart of classical random walks,
is an advanced tool for building quantum algorithms that has been recently
shown to constitute a universal model of quantum computation. Quantum walks is
now a solid field of research of quantum computation full of exciting open
problems for physicists, computer scientists, mathematicians and engineers.
In this paper we review theoretical advances on the foundations of both
discrete- and continuous-time quantum walks, together with the role that
randomness plays in quantum walks, the connections between the mathematical
models of coined discrete quantum walks and continuous quantum walks, the
quantumness of quantum walks, a summary of papers published on discrete quantum
walks and entanglement as well as a succinct review of experimental proposals
and realizations of discrete-time quantum walks. Furthermore, we have reviewed
several algorithms based on both discrete- and continuous-time quantum walks as
well as a most important result: the computational universality of both
continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing
Journa
Interleukin 6 in autoimmune and inflammatory diseases: a personal memoir
In this review, the author discusses the research that led to the identification and characterization of interleukin 6 (IL-6), including his own experience isolating IL-6, and the roles this cytokine has on autoimmune and inflammatory diseases. The cDNAs encoding B-cell stimulatory factor 2 (BSF-2), interferon (IFN)-ÎČ2 and a 26-kDa protein were independently cloned in 1986, which in turn led to the identification of each. To resolve the confusing nomenclature, these identical molecules were named IL-6. Characterization of IL-6 revealed a multifunctional cytokine that is involved in not only immune responses but also hematopoiesis, inflammation, and bone metabolism. Moreover, IL-6 makes significant contributions to such autoimmune and inflammatory diseases as rheumatoid arthritis (RA)
Searching for novel cerebrospinal fluid biomarkers of tau pathology in frontotemporal dementia: an elusive quest
BACKGROUND: Frontotemporal dementia (FTD) is a pathologically heterogeneous neurodegenerative disorder associated usually with tau or TDP-43 pathology, although some phenotypes such as logopenic variant primary progressive aphasia are more commonly associated with Alzheimer's disease pathology. Currently, there are no biomarkers able to diagnose the underlying pathology during life. In this study, we aimed to investigate the potential of novel tau species within cerebrospinal fluid (CSF) as biomarkers for tau pathology in FTD. METHODS: 86 participants were included: 66 with a clinical diagnosis within the FTD spectrum and 20 healthy controls. Immunoassays targeting tau fragments N-123, N-mid-region, N-224 and X-368, as well as a non-phosphorylated form of tau were measured in CSF, along with total-tau (T-tau) and phospho-tau (P-tau(181)). Patients with FTD were grouped based on their AÎČ42 level into those likely to have underlying Alzheimer's disease (AD) pathology (n=21) and those with likely frontotemporal lobar degeneration (FTLD) pathology (n=45). The FTLD group was then subgrouped based on their underlying clinical and genetic diagnoses into those with likely tau (n=7) or TDP-43 (n=18) pathology. RESULTS: Significantly higher concentrations of tau N-mid-region, tau N-224 and non-phosphorylated tau were seen in both the AD group and FTLD group compared with controls. However, none of the novel tau species showed a significant difference between the AD and FTLD groups, nor between the TDP-43 and tau pathology groups. In a subanalysis, normalising for total-tau, none of the novel tau species provided a higher sensitivity and specificity to distinguish between tau and TDP-43 pathology than P-tau(181)/T-tau, which itself only had a sensitivity of 61.1% and specificity of 85.7% with a cut-off of <0.109. CONCLUSIONS: Despite investigating multiple novel CSF tau fragments, none show promise as an FTD biomarker and so the quest for in vivo markers of FTLD-tau pathology continues
Corporate manslaughter: An examination of the determinants of prosecutorial policy
Although the offence of corporate manslaughter has arguably been established in English law for over twenty five years, it has been prosecuted only twice and both indictments failed. There is, however, much prima facie evidence to implicate companies in reckless manslaughter.
The purpose of this paper is to present an explanation of why companies which appear to commit homicide have been treated with conspicuous indulgence by the state.
I begin by examining the evidence that incriminates companies in homicide. I look at how the state has responded to these deaths with marked leniency. A brief account is given of the historical development of corporate liability in this area. The state's prosecutorial policy is then considered from three perspectives, moving outwards from close focus to a wide historical angle: I examine (a) the mechanics of the criminal justice system, its procedures and the decisions of its personnel; (b) the role of public perception in influencing those decisions and (c) the aspects of the political economy which engender the public perception in question
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