8,444 research outputs found

    Generalized Uncertainty Principle and Self-Adjoint Operators

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    In this work we explore the self-adjointness of the GUP-modified momentum and Hamiltonian operators over different domains. In particular, we utilize the theorem by von-Newmann for symmetric operators in order to determine whether the momentum and Hamiltonian operators are self-adjoint or not, or they have self-adjoint extensions over the given domain. In addition, a simple example of the Hamiltonian operator describing a particle in a box is given. The solutions of the boundary conditions that describe the self-adjoint extensions of the specific Hamiltonian operator are obtained.Comment: v1: 22 pages, LaTeX, revtex4; v2: 19 pages, minor corrections, to appear in Annals of Physic

    An R Package for Assessing Drug Synergism/Antagonism

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    Synergistic and antagonistic drug interactions are important to consider when developing mixtures of anticancer or other types of drugs. Boik, Newman, and Boik (2008) proposed the MixLow method as an alternative to the Median-Effect method of Chou and Talalay (1984) for estimating drug interaction indices. One advantage of the MixLow method is that the nonlinear mixed-effects model used to estimate parameters of concentration-response curves can provide more accurate parameter estimates than the log linearization and least-squares analysis used in the Median-Effect method. This paper introduces the mixlow package in R, an implementation of the MixLow method. Results are reported for a small simulation study.

    The Library of Babel

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    We show that heavy pure states of gravity can appear to be mixed states to almost all probes. Our arguments are made for AdS5\rm{AdS}_5 Schwarzschild black holes using the field theory dual to string theory in such spacetimes. Our results follow from applying information theoretic notions to field theory operators capable of describing very heavy states in gravity. For certain supersymmetric states of the theory, our account is exact: the microstates are described in gravity by a spacetime ``foam'', the precise details of which are invisible to almost all probes.Comment: 7 pages, 1 figure, Essay receiving honorable mention in the 2005 Gravity Research Foundation essay competitio

    Confirmation of a crisis leadership model and its effectiveness: lessons from the COVID-19 pandemic

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    Despite the significance of crisis leadership for organizations, especially in the wake of COVID-19, empirical research in this area is still nascent. Therefore, “What attributes make an effective leader during a crisis?” is unclear. Using lessons learned from the COVID-19 pandemic, this study seeks to address this gap in the literature by i) developing and validating a robust multi-dimensional crisis leadership model and ii) measure its effectiveness in handling the crisis. A higher-order measurement model of crisis leadership comprising of seven constructs (compassion and care, openness and communication, resilience and courage, decisiveness, consultation and collaboration, and empowerment) and two structural models to measure its predictive validity (effectiveness in handling the crisis) were proposed based on the review of crisis leadership literature. Next, using data collected through a global survey, the validity of the proposed models, including the relevance/appropriateness of each construct and the predictive power of the crisis leadership model in explaining the organizations’ effectiveness in handling the crisis, were assessed. The second-order confirmatory factor analysis established the existence of a higher-order measurement model for crisis leadership, with each of the seven constructs contributing uniquely and strongly. The structural equation modeling results confirmed the strong predictive power of the crisis leadership model in explaining the organizations’ effectiveness in handling the crisis across its different (beginning, current, and future) phases. The findings show that crisis leadership is multifaceted and requires an all-encompassing effort and provides a road map for organizations looking to develop crisis leadership capabilities for senior managers and leaders

    Drag of two-dimensional small-amplitude symmetric and asymmetric wavy walls in turbulent boundary layers

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    Included are results of an experimental investigation of low-speed turbulent flow over multiple two-dimensional transverse rigid wavy surfaces having a wavelength on the order of the boundary-layer thickness. Data include surface pressure and total drag measurements on symmetric and asymmetric wall waves under a low-speed turbulent boundary-layer flow. Several asymmetric wave configurations exhibited drag levels below the equivalent symmetric (sine) wave. The experimental results compare favorably with numerical predictions from a Reynolds-averaged Navier-Stokes spectral code. The reported results are of particular interest for the estimation of drag, the minimization of fabrication waviness effects, and the study of wind-wave interactions

    Physiology in aquaculture with special reference to penaeid shrimp aquaculture- Winter School on Recent Advances in Breeding and Larviculture of Marine Finfish and Shellfish

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    Aquaculture has been practiced in some societies for many centuries. However, the transition from low-input, pond-based capture system to more intensive and industrialized method has been done only during the last few decades. Contrary to terrestrial agriculture systems, aquaculture is a new industry with limited scientific knowledge. This is especially true for shrimp aquaculture, the fast growing and most valued food production systems of the world. Shrimp aquaculture has been developed without sufficient understanding of basic physiology of species of interest. Physiology is a powerful science, which has potential to contribute positively for the development and growth of aquaculture. The more understanding of the physiological processes that underlie crop performance leads to the improvement and optimization of aquaculture production. Further, as knowledge of physiological process expands, desirable traits can be identified, and that can be utilized as selection criteria. Incorporation of physiological traits for selection in breeding programme, thus, would help to achieve results more quickly and efficiently than selecting for yield performance alone. This lecture note provides an overview of various aspects of reproductive physiology that have direct application in optimizing aquaculture production. The possibilities of selecting physiological traits in breeding programme have also been discussed

    Breeding and larval rearing of mud crab- Winter School on Recent Advances in Breeding and Larviculture of Marine Finfish and Shellfish

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    Aquaculture of mud crabs (Scylla spp.) dates back to 1890 in Guangdong, China (Shan and Lain 1994). Since 1970s onwards, a steady interest was noticed in mud crabs culture in many tropical Asian countries due to its importantance in the industry and advantages viz. (1) uncomplicated technology, (2) abandoned shrimp ponds can be converted, (3) international markets, (4) native species to many tropical Asian countries, (5) easy transportation, potential for rural as well as industrialized aquaculture, (6) individual animals are valued in contrast to penaeid shrimps and (7) resilience of resources. However, crab aquaculture is severely constrained by the unperfected hatchery technology. This article summarizes various aspects of mud crab biology and hatchery technology

    Towards the Classification of Non-Marginal Bound States of M-branes and Their Construction Rules

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    We present a systematic analysis of possible bound states of M-brane solutions (including waves and monopoles) by using the solution generating technique of reduction of M-brane to 10 dimensions, use of T-duality and then lifting back to 11 dimensions. We summarize a list of bound states for one- and two-charge cases including tilted brane solutions. Construction rules for these non-marginal solutions are also discussed.Comment: Latex, 37 page

    Blood diamonds and ethical consumerism: an empirical investigation

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    Although ethical consumerism has witnessed significant interest in recent years, most studies have focused on low-value, commoditized product categories such as food and beverage and apparel. Despite its significance, the research on ethical consumerism in luxury product segments such as diamonds is relatively scant. This formed the motivation of this study, which examined the ethical buying behavior of consumers and the moderating effects of their income levels in the diamond industry. Four hundred eightteen responses toa structured questionnaire were collected. The framework comprising of four constructs, namely ethically-minded consumer behavior, willingness to pay more, ethical concerns regarding country of origin of diamonds, and ethical buying behavior of diamonds was first validated, and then the hypothesized relationships between the constructs were assessed using structural equation modeling. Overall, ethically minded consumer behavior had a significant positive impact on willingness to pay more, ethical concerns regarding the country of origin of diamonds, and ethical buying of diamonds. Additionally, ethical concerns regarding country of origin positively influenced the ethical buying of diamonds, while the willingness to pay more had no significant impact on ethical diamond purchases. The multi-group moderation test results revealed that the income levels of buyers do affect the relationships between constructs. For instance, for the middle income group, generic ethically-minded consumer behavior did not translate into the ethical buying behavior of diamonds. The findings provide useful insights for practitioners and policy-makers regarding ethical consumerism in the diamond industry and help to highlight the issues facing the industry, such as its poor supply chain transparency, human rights abuses, child labor, money laundering, bribery and corruption, and environmental degradation from mining activities
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