1,803 research outputs found
Status of direct searches for WIMP dark matter
Astrophysical observations indicate that about 23% of the energy density of
the universe is in the form of non-baryonic particles beyond the standard model
of particle physics. One exciting and well motivated candidate is the lightest
supersymmetric partner particle (LSP), which could be a weakly interacting
massive particle (WIMP) left over from the Big Bang. To determine that the LSP
is the dark matter, it is necessary both to measure the particle's properties
at an accelerator and to detect the particle in the galaxy directly (or
indirectly). Direct detection of these particles requires sophisticated
detectors to defeat much higher-rate backgrounds due to radioactivity and other
sources. Promising techniques identify individual interactions in shielded
fiducial volumes and distinguish nuclear-recoil signal events from
electron-recoil backgrounds, based on the timing, energy density, and/or the
division of the energy into signals of ionization, scintillation, or phonons. I
review the techniques of the dozens of experiments searching for WIMPs and
summarize the most interesting results and prospects for detection.Comment: 8 pages, 3 figures, to appear in Proceedings of SUSY06, the 14th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions, UC Irvine, California, 12-17 June 200
Introduction to dark matter experiments
This is a set of four lectures presented at the Theoretical Advanced Study
Institute (TASI-09) in June 2009. I provide an introduction to experiments
designed to detect WIMP dark matter directly, focusing on building intuitive
understanding of the characteristics of potential WIMP signals and the
experimental techniques. After deriving the characteristics of potential
signals in direct-detection experiments for standard WIMP models, I summarize
the general experimental methods shared by most direct-detection experiments
and review the advantages, challenges, and status of such searches (as of late
2009). Experiments are already probing SUSY models, with best limits on the
spin-independent coupling below 10^-7 pb.Comment: 64 pages, 25 figures, based on lectures at 2009 Theoretical Advanced
Study Institute in Elementary Particle Physics (TASI), Boulder, Colorado.
This posted version benefits from some editing relative to the version in the
published proceeding
The Dust Emissivity Spectral Index in the Starless Core TMC-1C
In this paper we present a dust emission map of the starless core TMC-1C
taken at 2100 microns. Along with maps at 160, 450, 850 and 1200 microns, we
study the dust emissivity spectral index from the (sub)millimeter spectral
energy distribution, and find that it is close to the typically assumed value
of beta = 2. We also map the dust temperature and column density in TMC-1C, and
find that at the position of the dust peak (A_V ~ 50), the
line-of-sight-averaged temperature is ~7 K. Employing simple Monte Carlo
modeling, we show that the data are consistent with a constant value for the
emissivity spectral index over the whole map of TMC-1C.Comment: 11 pages, including 5 pages of figures. Accepted to Ap
Interest Deduction for Individuals: Review and Update
This article will review the current cases and rulings involving business, investment and qualified residence interest. It will point out areas of uncertainty as well as planning opportunities and pitfalls
Conceptual frameworks in historical analysis: using reputation as interpretive prism
Purpose
This paper aims to advocate a revised perspective in historical analysis. The author calls for historians to apply the concept of reputation as interpretive lens in the analysis of historical processes and outcomes.
Design/methodology/approach
Widely used in management and marketing writing, but also relied upon in political science, the concept of reputation helps predict behaviour of individuals and entities that are bound by political constraints to align their actions to the goal of generating a popular standing. The lens also serves to cast light on the actions engaged in by external stakeholders that are informed by reputational cues. This theoretical contention is illustrated in four case studies resulting from investigations into political decisions and military conflicts, both in the republican and imperial period that ascertain how success and expansion as well as failure and decline of ancient Rome can be viewed and better understood by applying reputation as an instrument to direct and focus historical analysis.
Findings
This paper does not only advance complementary angles and alternative answers to issues in ancient Roman history. The cases considered also demonstrate how failure to recognise reputation as a significant concept in historical analysis does not only impair a comprehensive and balanced reflection of personal and organisational stakeholder behaviour but also thwarts a full appreciation of the motivation that drives individual protagonists and institutional agents, whose decisions are central to historical processes and outcomes.
Originality/value
The findings advanced in this paper – informed by four case studies – evidence the need of a new analytical prism in historical enquiry that will define the questions raised and direct the researcher’s attention. It has been shown how the concept of reputation can play a tangible role in sketching out a distinct new angle in historical investigation that leads to reviewing current narrative of past events and phenomena
Understanding a leader’s behaviour: Revisiting the role of reputation management in leadership research
This paper argues for the adoption of reputation as a conceptual prism to discern patterns in political leadership behaviour. The author intends to reach a judgement about the concept’s value for our understanding of leadership by offering a fuller appreciation of reputation itself that is grounded in a recognition of its role in managing followers and entrenching power structures, which makes it critical both to the incumbent leader and challengers. Methodologically, for this analysis both theoretical and descriptive materials have been selected and discussed in order to fully appreciate reputation’s applicability in leadership research. In light of the evidence reviewed one may infer that what renders a leader decisive or passive is essentially a reflection of reputational strength or weakness. In turn this leads us to conclude that concern with reputation engenders and shapes activity we observe in leaders and at the same time guides our interpretation of political decisions and phenomena. Eventually, we may come to see reputation as a concept that serves as a lens through which we view leaders’ responses to challenges. The rationale for this approach is leaders’ own focus on their respective reputation that may at times incentivise action or, alternatively, administrative and political immobility
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