424 research outputs found
THE ROLE OF PATH DEPENDENCE IN THE BUSINESS MODEL ADAPTATION: FROM TRADITIONAL TO DIGITAL BUSINESS MODELS
The digital context has driven new prospects of value creation and capture thus challenging and disrupting the traditional business models. Organizations need business models to transform the specific inherent logic of digital information products into new ways of creating economic value creation and appropriation. Thus, the business model change is an imperative for organizations to exploit value creation opportunities and to survive. Over time, however, business models become deeply embedded and they represent the dominant logic of the organization. Moreover the shift to the digital context poses additional cognitive constrains due to the characteristics inherent in digital information products that are quite distinct from the conventional ones, hence requiring a fundamental shift of dominant logic. This proposed study aims to explore the role of cognitive path dependencies originating in the non-digital context as an isolating mechanism in the process of creation of new digital business mode
Optimized pulses for the control of uncertain qubits
Constructing high-fidelity control fields that are robust to control, system,
and/or surrounding environment uncertainties is a crucial objective for quantum
information processing. Using the two-state Landau-Zener model for illustrative
simulations of a controlled qubit, we generate optimal controls for \pi/2- and
\pi-pulses, and investigate their inherent robustness to uncertainty in the
magnitude of the drift Hamiltonian. Next, we construct a quantum-control
protocol to improve system-drift robustness by combining environment-decoupling
pulse criteria and optimal control theory for unitary operations. By
perturbatively expanding the unitary time-evolution operator for an open
quantum system, previous analysis of environment-decoupling control pulses has
calculated explicit control-field criteria to suppress environment-induced
errors up to (but not including) third order from \pi/2- and \pi-pulses. We
systematically integrate this criteria with optimal control theory,
incorporating an estimate of the uncertain parameter, to produce improvements
in gate fidelity and robustness, demonstrated via a numerical example based on
double quantum dot qubits. For the qubit model used in this work, post facto
analysis of the resulting controls suggests that realistic control-field
fluctuations and noise may contribute just as significantly to gate errors as
system and environment fluctuations.Comment: 38 pages, 15 figures, RevTeX 4.1, minor modifications to the previous
versio
Vaporous marketing: Uncovering pervasive electronic cigarette advertisements on twitter
Background Twitter has become the wild-west of marketing and promotional strategies for advertisement agencies. Electronic cigarettes have been heavily marketed across Twitter feeds, offering discounts, kid-friendly flavors, algorithmically generated false testimonials, and free samples. Methods All electronic cigarette keyword related tweets from a 10% sample of Twitter spanning January 2012 through December 2014 (approximately 850,000 total tweets) were identified and categorized as Automated or Organic by combining a keyword classification and a machine trained Human Detection algorithm. A sentiment analysis using Hedonometrics was performed on Organic tweets to quantify the change in consumer sentiments over time. Commercialized tweets were topically categorized with key phrasal pattern matching. Results The overwhelming majority (80%) of tweets were classified as automated or promotional in nature. The majority of these tweets were coded as commercialized (83.65% in 2013), up to 33% of which offered discounts or free samples and appeared on over a billion twitter feeds as impressions. The positivity of Organic (human) classified tweets has decreased over time (5.84 in 2013 to 5.77 in 2014) due to a relative increase in the negative words \u27ban\u27, \u27tobacco\u27, \u27doesn\u27t\u27, \u27drug\u27, \u27against\u27, \u27poison\u27, \u27tax\u27 and a relative decrease in the positive words like \u27haha\u27, \u27good\u27, \u27cool\u27. Automated tweets are more positive than organic (6.17 versus 5.84) due to a relative increase in the marketing words like \u27best\u27, \u27win\u27, \u27buy\u27, \u27sale\u27, \u27health\u27, \u27discount\u27 and a relative decrease in negative words like \u27bad\u27, \u27hate\u27, \u27stupid\u27, \u27don\u27t\u27. Conclusions Due to the youth presence on Twitter and the clinical uncertainty of the long term health complications of electronic cigarette consumption, the protection of public health warrants scrutiny and potential regulation of social media marketing
Calculations of time-dependent observables in non-Hermitian quantum mechanics: The problem and a possible solution
The solutions of the time independent Schrodinger equation for non-Hermitian
(NH) Hamiltonians have been extensively studied and calculated in many
different fields of physics by using L^2 methods that originally have been
developed for the calculations of bound states. The existing non-Hermitian
formalism breaks down when dealing with wavepackets(WP). An open question is
how time dependent expectation values can be calculated when the Hamiltonian is
NH ? Using the F-product formalism, which was recently proposed, [J. Phys.
Chem., 107, 7181 (2003)] we calculate the time dependent expectation values of
different observable quantities for a simple well known study test case model
Hamiltonian. We carry out a comparison between these results with those
obtained from conventional(i.e., Hermitian) quantum mechanics (QM)
calculations. The remarkable agreement between these results emphasizes the
fact that in the NH-QM, unlike standard QM, there is no need to split the
entire space into two regions; i.e., the interaction region and its
surrounding. Our results open a door for a type of WP propagation calculations
within the NH-QM formalism that until now were impossible.Comment: 20 pages, 5 Postscript figures. To be Published in Physical Review
Quantum reactive scattering calculations of cross sections and rate constants for the N(2D) + O2(X3Σg-) → O(3Π) + NO(X2Π) reaction
Time-dependent quantum wavepacket calculations have been performed on the two lowest adiabatic potential energy surfaces (2 2A´ and 1 2A˝) for the N(2D) + O2(X3Σg-) → O(3Π) + NO(X2Π) reaction. The calculations have been carried out, on these recently published potential energy surfaces, using the real wavepacket method together with a new dispersion fitted finite difference technique for evaluating the action of the radial kinetic energy operator. Reaction probabilities, corresponding to the O2 reactant in its ground vibrational-rotational state, have been calculated for both surfaces and for many different values of the total angular momentum quantum number (J), within the helicity decoupling approximation. The reaction probabilities associated with all other relevant J values have been interpolated, and to a smaller extent extrapolated, using a capture model, to yield probabilities as a function of energy. The probabilities have in turn been summed to yield energy dependent cross sections and then used to compute rate constants. These rate constants are compared with ones obtained from quasiclassical trajectory (QCT) and variational transition state theory (VTST) calculations performed on the same surfaces. There is a good agreement between the wavepacket and QCT cross sections for reaction on both potential energy surfaces considered, with the exception of the near threshold region, where the reaction probability is dominated by tunnelling. Comparison of the predicted rate constants shows that for the 2 2A´ surface, above 300 K, the wavepacket, QCT and VTST results are quite similar. For the 1 2A˝ surface, however, significant differences occur between the wavepacket and the other methods. These differences become smaller with increasing temperature. It is likely that these differences arise, at least in part, from the fact that, when calculating the rate constants, the reactants are restricted to be in their lowest vibrational-rotational state in the wavepacket calculations but are selected from a thermally equilibrated population in the other methods
Acute supplementation of N-acetylcysteine does not affect muscle blood flow and oxygenation characteristics during handgrip exercise
Citation: Smith, J. R., Broxterman, R. M., Ade, C. J., Evans, K. K., Kurti, S. P., Hammer, S. M., . . . Harms, C. A. (2016). Acute supplementation of N-acetylcysteine does not affect muscle blood flow and oxygenation characteristics during handgrip exercise. Physiological Reports, 4(7), 1-10. doi:10.14814/phy2.12748N-acetylcysteine (NAC; antioxidant and thiol donor) supplementation has improved exercise performance and delayed fatigue, but the underlying mechanisms are unknown. One possibility is NAC supplementation increases limb blood flow during severe-intensity exercise. The purpose was to determine if NAC supplementation affected exercising arm blood flow and muscle oxygenation characteristics. We hypothesized that NAC would lead to higher limb blood flow and lower muscle deoxygenation characteristics during severe-intensity exercise. Eight healthy nonendurance trained men (21.8 ± 1.2 years) were recruited and completed two constant power handgrip exercise tests at 80% peak power until exhaustion. Subjects orally consumed either placebo (PLA) or NAC (70 mg/kg) 60 min prior to handgrip exercise. Immediately prior to exercise, venous blood samples were collected for determination of plasma redox balance. Brachial artery blood flow (BABF) was measured via Doppler ultrasound and flexor digitorum superficialis oxygenation characteristics were measured via near-infrared spectroscopy. Following NAC supplementaiton, plasma cysteine (NAC: 47.2 ± 20.3 ?mol/L vs. PLA: 9.6 ± 1.2 ?mol/L; P = 0.001) and total cysteine (NAC: 156.2 ± 33.9 ?mol/L vs. PLA: 132.2 ± 16.3 ?mol/L; P = 0.048) increased. Time to exhaustion was not significantly different (P = 0.55) between NAC (473.0 ± 62.1 sec) and PLA (438.7 ± 58.1 sec). Resting BABF was not different (P = 0.79) with NAC (99.3 ± 31.1 mL/min) and PLA (108.3 ± 46.0 mL/min). BABF was not different (P = 0.42) during exercise or at end-exercise (NAC: 413 ± 109 mL/min; PLA: 445 ± 147 mL/min). Deoxy-[hemoglobin+myoglobin] and total-[hemoglobin+myoglobin] were not significantly different (P = 0.73 and P = 0.54, respectively) at rest or during exercise between conditions. We conclude that acute NAC supplementation does not alter oxygen delivery during exercise in men. © 2016 Published by the American Physiological Society and The Physiological Society
Resistance loci affecting distinct stages of fungal pathogenesis: use of introgression lines for QTL mapping and characterization in the maize - Setosphaeria turcica pathosystem
<p>Abstract</p> <p>Background</p> <p>Studies on host-pathogen interactions in a range of pathosystems have revealed an array of mechanisms by which plants reduce the efficiency of pathogenesis. While R-gene mediated resistance confers highly effective defense responses against pathogen invasion, quantitative resistance is associated with intermediate levels of resistance that reduces disease progress. To test the hypothesis that specific loci affect distinct stages of fungal pathogenesis, a set of maize introgression lines was used for mapping and characterization of quantitative trait loci (QTL) conditioning resistance to <it>Setosphaeria turcica</it>, the causal agent of northern leaf blight (NLB). To better understand the nature of quantitative resistance, the identified QTL were further tested for three secondary hypotheses: (1) that disease QTL differ by host developmental stage; (2) that their performance changes across environments; and (3) that they condition broad-spectrum resistance.</p> <p>Results</p> <p>Among a set of 82 introgression lines, seven lines were confirmed as more resistant or susceptible than B73. Two NLB QTL were validated in BC<sub>4</sub>F<sub>2 </sub>segregating populations and advanced introgression lines. These loci, designated <it>qNLB1.02 </it>and <it>qNLB1.06</it>, were investigated in detail by comparing the introgression lines with B73 for a series of macroscopic and microscopic disease components targeting different stages of NLB development. Repeated greenhouse and field trials revealed that <it>qNLB1.06<sub>Tx303 </sub></it>(the Tx303 allele at bin 1.06) reduces the efficiency of fungal penetration, while <it>qNLB1.02<sub>B73 </sub></it>(the B73 allele at bin 1.02) enhances the accumulation of callose and phenolics surrounding infection sites, reduces hyphal growth into the vascular bundle and impairs the subsequent necrotrophic colonization in the leaves. The QTL were equally effective in both juvenile and adult plants; <it>qNLB1.06<sub>Tx303 </sub></it>showed greater effectiveness in the field than in the greenhouse. In addition to NLB resistance, <it>qNLB1.02<sub>B73 </sub></it>was associated with resistance to Stewart's wilt and common rust, while <it>qNLB1.06<sub>Tx303 </sub></it>conferred resistance to Stewart's wilt. The non-specific resistance may be attributed to pleiotropy or linkage.</p> <p>Conclusions</p> <p>Our research has led to successful identification of two reliably-expressed QTL that can potentially be utilized to protect maize from <it>S. turcica </it>in different environments. This approach to identifying and dissecting quantitative resistance in plants will facilitate the application of quantitative resistance in crop protection.</p
Gonococcal Acute Septic Arthritis in Immunocompetent Patients
The objective of this study is to estimate the clinical evolution and the biological values and of three cases suffering from Gonococcal acute septic arthritis (GASA).Our study is based in a thoroughfully screening of 18 patients hospitalized in our service during the period of time of March 2011 – July 2016. Among those 18 cases, 12 of them (66.7%) were diagnosed with Acute Septic Arthritis (ASA) due to Staphylococcus aureus, 3 cases (16.65%) were diagnosed with ASA due to Neisseria gonorrhoeae, and 3 other cases (16.65%) were diagnosed with ASA due to Streptococcus pneumoniae, Escherichia coli and Echinella corrodens. Two sexually active women at the seventh and tenth day of an untreated suppurative cervico-vaginitis and one man at the eighth day of an untreated suppurative urethritis were consulted at the Service of Infectious Diseases of University Hospital Center “Mother Theresa”, because of: severe pains in left wrist, in the left elbow and in the right knee, swollen of those articulation, difficulties in their movements, shivering and a high fever of  38-39.2ºC. Neisseria gonorrhea was insolated in three cases in blood cultures and cervical/urethral samples and they were sensitive towards Cyclines, Cephalosporins and Fluoroquinolones. All three patients were immunocompetent. Keywords: Neisseria gonorrhea, Acute Septic Arthritis, Biological values
- …