Ethical Responses: How to Influence One\u27s Organization

Faced with moral conflict or unethical behavior within an organization, an individual who objects has a choice of three possible responses­-exit, voice, and loyalty. The choice and the intensity of pursuit of that choice affect the organization as well as the individual differently. This article examines the factors affecting the availability and appropriateness of each. Neither the bases for morality nor the circumstances which create ethical dilemmas are the focus of this review

Unusual electron correlations in NaxCoO2 due to the spin-state quasidegeneracy of cobalt ions

Recent studies exposed many remarkable properties of layered cobaltates NaxCoO2. Surprisingly, many-body effects have been found to increase at sodium-rich compositions of NaxCoO2 where one expects a simple, nearly free motion of the dilute S=1/2 holes doped into a band insulator NaCoO2. Here we discuss the origin of enigmatic correlations that turn a doped NaCoO2 into a strongly correlated electronic system. A minimal model including orbital degeneracy is proposed and its predictions are discussed. The model is based on a key property of cobalt oxides - the spin-state quasidegeneracy of CoO6 octahedral complex - which has been known, e.g., in the context of an unusual physics of LaCoO3 compound. Another important ingredient of the model is the 90-degree Co-O-Co bonding in NaxCoO2 which allows nearest-neighbor $t_{2g}-e_g$ hopping. This hopping introduces a dynamical mixture of electronic configurations $t_{2g}^6, S=0$ and $t_{2g}^5e_g^1, S=1$ of neighboring cobalt ions. We show that scattering of charge carriers on spin-state fluctuations suppresses their coherent motion and leads to the spin-polaron physics at $x\sim 1$. At larger doping when coherent fermionic bands are formed, the model predicts singlet superconductivity of extended s-wave symmetry. The presence of low-lying spin states of Co$^{3+}$ is essential for the pairing mechanism. Implications of the model for magnetic orderings are also discussed.Comment: 27 pages, 19 figures, submitted to Progress of Theoretical Physics Supplemen

Hypervelocity impact facility for simulating materials exposure to impact by space debris

As a result of man's venturing into space, the local debris contributed by his presence exceeds, at some orbital altitudes, that of the natural component. Man's contribution ranges from fuel residue to large derelect satellites that weigh many kilograms. Current debris models are able to predict the growth of the problem and suggest that spacecraft must employ armor or bumper shields for some orbital altitudes now, and that, the problem will become worse as a function of time. The practical upper limit to the velocity distribution is on the order of 40 km/s and is associated with the natural environment. The maximum velocity of the man-made component is in the 14-16 km/s range. The Long Duration Exposure Facility (LDEF) has verified that the 'high probability of impact' particles are in the microgram to milligram range. These particles can have significant effects on coatings, insulators, and thin metallic layers. The surface of thick materials becomes pitted and the local debris component is enhanced by ejecta from the debris spectrum in a controlled environment. The facility capability is discussed in terms of drive geometry, energetics, velocity distribution, diagnostics, and projectile/debris loading. The facility is currently being used to study impact phenomena on Space Station Freedom's solar array structure, other solar array materials, potential structural materials for use in the station, electrical breakdown in the space environment, and as a means of clarifying or duplicating the impact phenomena on the LDEF surfaces. The results of these experiments are described in terms of the mass/velocity distribution incident on selected samples, crater dynamics, and sample geometry

Socioeconomic Differences in the Impact of Smoking Tobacco and Alcohol Prices on Smoking in India

The threat posed by smoking to health in India is severe. Already 1 in 5 of all adult male deaths and 1 in 20 of all adult female deaths at ages 30-69 are due to smoking and India will soon have 1 million smoking deaths a year. Increasing tobacco prices has been found to be the single most effective method to reduce smoking. Yet, bidis, the most common form of smoked tobacco in India, are largely untaxed, while cigarettes are taxed at about 40% of retail price, well below the 65–80% rate noted by the World Bank in countries with effective tobacco control policies. Moreover, low and stagnant tax rates have occurred in a period in which all tobacco products have become more affordable with income growth. First, we use data from the most recent three consecutive quinquennial National Sample Survey (NSS) rounds (NSS 50, 55 and 61 conducted in 1993/94, 1999/00 and 200/05) and a two-equation system of budget shares and unit values that attempts to correct for quality and measurement error. Second, we pool data from the most recent nine rounds of NSS (NSS 55-57, 59-64, conducted between 1999/00 to 2007/08). Our analyses of single and repeated cross-sections yield own-price elasticity for bidis that are roughly in keeping with existing evidence. We find that a 10% increase in bidi prices would reduce the demand for bidis by about 6 to 9.5%. We find, however, that own-price elasticity for cigarettes in India is substantially larger than previously thought. Our estimates suggest that cigarette users are at least as responsive as bidi users to price changes. On the whole, our analyses suggest that low SES households are likely more responsive to price changes than high SES households. Our analyses also uncovers important and policy-relevant cross-prices effects. Findings from this study provide additional evidence of the effectiveness of tobacco prices at reducing tobacco use.

Stretched Too Thin?: The Relationship Between Insufficient Resource Allocation and Physical Education Instructional Time and Assessment Practices

With provisions in the Every Student Succeeds Act, attention to physical education (PE) programs in school will be crucial for developing well-rounded students. We assessed the availability of resources that have the potential to impact PE (staffing, continuing education, annual PE equipment budgets) in a nationally-representative sample of 640 U.S. public elementary schools. Higher student-to-PE teacher ratios were associated with students not receiving adequate instruction. Equipment budgets were minimal (median = $500) and 30% of schools had no budget at all. Additional financial support from federal and state education agencies would help schools to better meet recommendations for PE

Grades of brain arteriovenous malformations and risk of hemorrhage and death

Objective: To assess the relationship of the grade of unruptured and untreated Brain Arteriovenous Malformations (AVMs), with the risk of subsequent stroke and death during follow-up. Methods: This prospective study was drawn from a cohort of adult patients with unruptured AVMs, who participated in the conservative treatment arm (medical management only for headache or seizures) of the randomized clinical trial of unruptured brain AVMs (ARUBA study). The grade of AVMs (Spetzler–Martin scale) was dichotomized into categories: AVMs of grades I and II were considered low grade; AVMs of grades III and IV were considered high grade. There were no grade V AVM patients in ARUBA. The primary outcome was symptomatic stroke (hemorrhagic or ischemic – documented by imaging) or death. Results: The conservative treatment group had 123 patients (“as treated” analysis). 71 (57.7%) had lesions characterized for this analysis as low-grade lesions and 52 (42.2%) as high grade. From the total of 10 (8.13%) primary outcomes, three occurred (4.22%) in low-grade AVMs and seven (13.46%) in high-grade AVMs (P = 0.0942). Interpretation: Statistical analysis of the cohort of patients with unruptured and untreated AVMs from ARUBA study showed that the graduation categories (Spetzler–Martin grades) were not associated with the outcome of subsequent stroke or death

Higgs mode and its decay in a two dimensional antiferromagnet

Condensed-matter analogs of the Higgs boson in particle physics allow insights into its behavior in different symmetries and dimensionalities. Evidence for the Higgs mode has been reported in a number of different settings, including ultracold atomic gases, disordered superconductors, and dimerized quantum magnets. However, decay processes of the Higgs mode (which are eminently important in particle physics) have not yet been studied in condensed matter due to the lack of a suitable material system coupled to a direct experimental probe. A quantitative understanding of these processes is particularly important for low-dimensional systems where the Higgs mode decays rapidly and has remained elusive to most experimental probes. Here, we discover and study the Higgs mode in a two-dimensional antiferromagnet using spin-polarized inelastic neutron scattering. Our spin-wave spectra of Ca$_2$RuO$_4$ directly reveal a well-defined, dispersive Higgs mode, which quickly decays into transverse Goldstone modes at the antiferromagnetic ordering wavevector. Through a complete mapping of the transverse modes in the reciprocal space, we uniquely specify the minimal model Hamiltonian and describe the decay process. We thus establish a novel condensed matter platform for research on the dynamics of the Higgs mode.Comment: original submitted version, Nature Physics (2017). arXiv admin note: substantial text overlap with arXiv:1510.0701

Will jets reduce the elliptic flow at LHC, while decays of resonances restore the constituent quark scaling?

Formation and evolution of the elliptic flow pattern in Pb+Pb collisions at sqrt{s}=5.5 ATeV and in Au+Au collisions at sqrt{s}=200 AGeV are analyzed for different hadron species within the framework of HYDJET++ Monte-Carlo model. The model contains both hydrodynamic state and jets, thus allowing for a study of the interplay between the soft and hard processes. It is found that jets are terminating the rise of the elliptic flow with increasing transverse momentum. Since jets are more influential at LHC compared to RHIC, the elliptic flow at LHC should be weaker than that at RHIC. The influence of resonance decays on particle elliptic flow is investigated also. These final state interactions enhance the low-p_T part of the v_2 of pions and light baryons, and work towards the fulfilment of idealized constituent quark scaling.Comment: 8 pages, 9 figures, 3 table

Direct Evidence for Dominant Bond-directional Interactions in a Honeycomb Lattice Iridate Na2IrO3

Heisenberg interactions are ubiquitous in magnetic materials and have been prevailing in modeling and designing quantum magnets. Bond-directional interactions offer a novel alternative to Heisenberg exchange and provide the building blocks of the Kitaev model, which has a quantum spin liquid (QSL) as its exact ground state. Honeycomb iridates, A2IrO3 (A=Na,Li), offer potential realizations of the Kitaev model, and their reported magnetic behaviors may be interpreted within the Kitaev framework. However, the extent of their relevance to the Kitaev model remains unclear, as evidence for bond-directional interactions remains indirect or conjectural. Here, we present direct evidence for dominant bond-directional interactions in antiferromagnetic Na2IrO3 and show that they lead to strong magnetic frustration. Diffuse magnetic x-ray scattering reveals broken spin-rotational symmetry even above Neel temperature, with the three spin components exhibiting nano-scale correlations along distinct crystallographic directions. This spin-space and real-space entanglement directly manifests the bond-directional interactions, provides the missing link to Kitaev physics in honeycomb iridates, and establishes a new design strategy toward frustrated magnetism.Comment: Nature Physics, accepted (2015