14,849 research outputs found
Power's mission: impact and the quest for goal achievement
This article discusses evidence linking power to purpose: that of having an impact in the social environment and carrying out individual or collective aims and desires. First, it highlights the role of goals during the emergence and the exercise of power. Accordingly, it suggests that typical power’s mission is to strive for social or personal objectives in social contexts. This includes social influence goals, organizational or personal agendas. Secondly, the article describes how power affects goal-related strategies and cognitive inclinations. Evidence suggests that power triggers prioritization and facilitates the pursuit of any salient goals, filtered by personal values and inclinations of the powerholder. Thirdly, the article examines powerholders’ effectiveness of goal pursuit, including their performance on tangible social tasks. Finally, the article ends with a discussion on non-intended consequences of the power-goal links in particular in the social domain
Phytochemical Constituents and Analgesic Activity of Ethyl Acetate Fraction of Punicagranatum L (Punicaceae)
Purpose: To investigate the active fraction of pomegranate fruit extract and screen it for analgesic activity.Methods: The analgesic activity of pomegranate ethyl acetate fraction (EtOAc) was examined using three models of pain: writhing, hot tail flick and plantar tests. EtOAc was administered by oral gavage in doses of 100, 150 and 200 mg/kg, p.o., for all the tests and compared to aspirin (100 mg/kg, p.o.) which was used as standard drug. Phytochemical studies of EtOAc were carried out by high performance liquid chromatography (HPLC) with ultraviolet (UV) detection and mass spectrometry (MS).Results: In the writhing test, the index of pain inhibition (IPI) was 41 % for EtOAc (200 mg/kg, p.o.) and 56 % for aspirin. In the hot tail flick test, EtOAc (200 mg/kg, p.o.) showed analgesia reaching its peak at 60 min with maximum possible analgesia (MPA) of 30.5 %, compared with 43.8 % for aspirin. Plantar test showed that pain was reduced by EtOAc in a dose-dependent manner and compared well with aspirin at 100 mg/kg, p.o., dose. The 200 mg/kg dose showed the highest effect, prolonging withdrawal latency in the left hind paw to 11.9 ± 0.3 compared to aspirin with 13.4 ± 0.2 (p < 0.001). HPLC analysis of EtOAc revealed the presence of gallic acid, ellagic acid and punicalagins A & B. Confirmation of their structures was achieved by mass spectroscopy.Conclusion: EtOAc has a central and peripheral analgesic effect that is most likely due to the presence of gallic acid and ellagic acid.Keywords: Analgesia, Pomegranate, Gallic acid, Ellagic acid, Punicalagins, Phytochemical constituent
On Ladder Logic Bombs in Industrial Control Systems
In industrial control systems, devices such as Programmable Logic Controllers
(PLCs) are commonly used to directly interact with sensors and actuators, and
perform local automatic control. PLCs run software on two different layers: a)
firmware (i.e. the OS) and b) control logic (processing sensor readings to
determine control actions). In this work, we discuss ladder logic bombs, i.e.
malware written in ladder logic (or one of the other IEC 61131-3-compatible
languages). Such malware would be inserted by an attacker into existing control
logic on a PLC, and either persistently change the behavior, or wait for
specific trigger signals to activate malicious behaviour. For example, the LLB
could replace legitimate sensor readings with manipulated values. We see the
concept of LLBs as a generalization of attacks such as the Stuxnet attack. We
introduce LLBs on an abstract level, and then demonstrate several designs based
on real PLC devices in our lab. In particular, we also focus on stealthy LLBs,
i.e. LLBs that are hard to detect by human operators manually validating the
program running in PLCs. In addition to introducing vulnerabilities on the
logic layer, we also discuss countermeasures and we propose two detection
techniques.Comment: 11 pages, 14 figures, 2 tables, 1 algorith
Microwave heating of carbon-based solid materials
As a part of the electromagnetic spectrum, microwaves heat materials fast and efficiently via direct energy transfer, while conventional heating methods rely on conduction and convection. To date, the use of microwave heating in the research of carbon-based materials has been mainly limited to liquid solutions. However, more rapid and efficient heating is possible in electron-rich solid materials, because the target materials absorb the energy of microwaves effectively and exclusively. Carbon-based solid materials are suitable for microwave-heating due to the delocalized pi electrons from sp2-hybridized carbon networks. In this perspective review, research on the microwave heating of carbon-based solid materials is extensively investigated. This review includes basic theories of microwave heating, and applications in carbon nanotubes, graphite and other carbon-based materials. Finally, priority issues are discussed for the advanced use of microwave heating, which have been poorly understood so far: heating mechanism, temperature control, and penetration depth.X1126Ysciescopu
GLOBAL RATES OF CONVERGENCE IN LOG-CONCAVE DENSITY ESTIMATION
The estimation of a log-concave density on Rd represents a central problem in the area of nonparametric inference under shape constraints. In this paper, we study the performance of log-concave density estimators with respect to global loss functions, and adopt a minimax approach. We first show that no statistical procedure based on a sample of size n can estimate a log-concave density with respect to the squared Hellinger loss function with supremum risk smaller than order n−4/5, when d=1, and order n−2/(d+1) when d≥2. In particular, this reveals a sense in which, when d≥3, log-concave density estimation is fundamentally more challenging than the estimation of a density with two bounded derivatives (a problem to which it has been compared). Second, we show that for d≤3, the Hellinger ε-bracketing entropy of a class of log-concave densities with small mean and covariance matrix close to the identity grows like max{ε−d/2,ε−(d−1)} (up to a logarithmic factor when d=2). This enables us to prove that when d≤3 the log-concave maximum likelihood estimator achieves the minimax optimal rate (up to logarithmic factors when d=2,3) with respect to squared Hellinger loss.The research of Richard J. Samworth was supported by an EPSRC Early Career Fellowship and a grant from the Leverhulme Trust
US public support for vaccine donation to poorer countries in the 2009 H1N1 pandemic
Background: During the 2009 H1N1 pandemic, the global health community sought to make vaccine available "in developing nations in the same timeframe as developed nations." However, richer nations placed advance orders with manufacturers, leaving poorer nations dependent on the quantity and timing of vaccine donations by manufacturers and rich nations. Knowledge of public support for timely donations could be important to policy makers during the next pandemic. We explored what the United States (US) public believes about vaccine donation by its country to poorer countries. Methods and Findings: We surveyed 2079 US adults between January 22 nd and February 1 st 2010 about their beliefs regarding vaccine donation to poorer countries. Income (p = 0.014), objective priority status (p = 0.005), nativity, party affiliation, and political ideology (p<0.001) were significantly related to views on the amount of vaccine to be donated. Though party affiliation and political ideology were related to willingness to donate vaccine (p<0.001), there was bipartisan support for timely donations of 10% of the US vaccine supply so that those "at risk in poorer countries can get the vaccine at the same time" as those at risk in the US. Conclusions: We suggest that the US and other developed nations would do well to bolster support with education and public discussion on this issue prior to an emerging pandemic when emotional reactions could potentially influence support for donation. We conclude that given our evidence for bipartisan support for timely donations, it may be necessary to design multiple arguments, from utilitarian to moral, to strengthen public and policy makers' support for donations. © 2012 Kumar et al
Effects of polarization mode dispersion on polarization-entangled photons generated via broadband pumped spontaneous parametric down-conversion
An inexpensive and compact frequency multi-mode diode laser enables a compact two-photon polarization entanglement source via the continuous wave broadband pumped spontaneous parametric down-conversion (SPDC) process. Entanglement degradation caused by polarization mode dispersion (PMD) is one of the critical issues in optical fiber-based polarization entanglement distribution. We theoretically and experimentally investigate how the initial entanglement is degraded when the two-photon polarization entangled state undergoes PMD. We report an effect of PMD unique to broadband pumped SPDC, equally applicable to pulsed pumping as well as cw broadband pumping, which is that the amount of the entanglement degradation is asymmetrical to the PMD introduced to each quantum channel. We believe that our results have important applications in long-distance distribution of polarization entanglement via optical fiber channels.1111Ysciescopu
Fluorescent Probes for Analysis and Imaging of Monoamine Oxidase Activity
Monoamine oxidases catalyze the oxidative deamination of dietary amines and amine neurotransmitters, and assist in maintaining the homeostasis of the amine neurotransmitters in the brain. Dysfunctions of these enzymes can cause neurological and behavioral disorders including Parkinson's and Alzheimer's diseases. To understand their physiological roles, efficient assay methods for monoamine oxidases are essential. Reviewed in this Perspective are the recent progress in the development of fluorescent probes for monoamine oxidases and their applications to enzyme assays in cells and tissues. It is evident that still there is strong need for a fluorescent probe with desirable substrate selectivity and photophysical properties to challenge the much unsolved issues associated with the enzymes and the diseases.X1132Ysciescopu
Experimental demonstration of high fidelity entanglement distribution over decoherence channels via qubit transduction
Quantum coherence and entanglement, which are essential resources for quantum information, are often degraded and lost due to decoherence. Here, we report a proof-of-principle experimental demonstration of high fidelity entanglement distribution over decoherence channels via qubit transduction. By unitarily switching the initial qubit encoding to another, which is insensitive to particular forms of decoherence, we have demonstrated that it is possible to avoid the effect of decoherence completely. In particular, we demonstrate high-fidelity distribution of photonic polarization entanglement over quantum channels with two types of decoherence, amplitude damping and polarization-mode dispersion, via qubit transduction between polarization qubits and dual-rail qubits. These results represent a significant breakthrough in quantum communication over decoherence channels as the protocol is input-state independent, requires no ancillary photons and symmetries, and has near-unity success probability.1132Ysciescopu
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