1,486 research outputs found
Simple model for scanning tunneling spectroscopy of noble metal surfaces with adsorbed Kondo impurities
A simple model is introduced to describe conductance measurements between a
scanning tunneling microscope (STM) tip and a noble metal surface with adsorbed
transition metal atoms which display the Kondo effect. The model assumes a
realistic parameterization of the potential created by the surface and a
d3z2-r2 orbital for the description of the adsorbate. Fano lineshapes
associated with the Kondo resonance are found to be sensitive to details of the
adsorbate-substrate interaction. For instance, bringing the adsorbate closer to
the surface leads to more asymmetric lineshapes while their dependence on the
tip distance is weak. We find that it is important to use a realistic surface
potential, to properly include the tunnelling matrix elements to the tip and to
use substrate states which are orthogonal to the adsorbate and tip states. An
application of our model to Co adsorbed on Cu explains the difference in the
lineshapes observed between Cu(100) and Cu(111) surfaces.Comment: 11 pages, 8 eps figure
Asymptotics and local constancy of characters of p-adic groups
In this paper we study quantitative aspects of trace characters
of reductive -adic groups when the representation varies. Our approach
is based on the local constancy of characters and we survey some other related
results. We formulate a conjecture on the behavior of relative to
the formal degree of , which we are able to prove in the case where
is a tame supercuspidal. The proof builds on J.-K.~Yu's construction and the
structure of Moy-Prasad subgroups.Comment: Proceedings of Simons symposium on the trace formul
A Library for Declarative Resolution-Independent 2D Graphics
The design of most 2D graphics frameworks has been guided by what the computer can draw efficiently, instead of by how graphics can best be expressed and composed. As a result, such frameworks restrict expressivity by providing a limited set of shape primitives, a limited set of textures and only affine transformations. For example, non-affine transformations can only be added by invasive modification or complex tricks rather than by simple composition. More general frameworks exist, but they make it harder to describe and analyze shapes. We present a new declarative approach to resolution-independent 2D graphics that generalizes and simplifies the functionality of traditional frameworks, while preserving their efficiency. As a real-world example, we show the implementation of a form of focus+context lenses that gives better image quality and better performance than the state-of-the-art solution at a fraction of the code. Our approach can serve as a versatile foundation for the creation of advanced graphics and higher level frameworks
Understanding the role of shame and its consequences in female hypersexual behaviours: A pilot study
Background and aims:
Hypersexuality and sexual addiction among females is a little understudied phenomenon. Shame is thought to be intrinsic to hypersexual behaviours, especially in women. Therefore, the aim of this study was to understand both hypersexual behaviours and consequences of hypersexual behaviours and their respective contributions to shame in a British sample of females (n = 102).
Methods:
Data were collected online via Survey Monkey.
Results:
Results showed the Sexual Behaviour History (SBH) and the Hypersexual Disorder Questionnaire (HDQ) had significant positive correlation with scores on the Shame Inventory. The results indicated that hypersexual behaviours (HBI and HDQ) were able to predict a small percentage of the variability in shame once sexual orientation (heterosexual vs. non-heterosexual) and religious beliefs (belief vs. no belief) were controlled for. Results also showed there was no evidence that religious affiliation and/or religious beliefs had an influence on the levels of hypersexuality and consequences of sexual behaviours as predictors of shame.
Conclusions:
While women in the UK are rapidly shifting to a feminist way of thinking with or without technology, hypersexual disorder may often be misdiagnosed and misunderstood because of the lack of understanding and how it is conceptualised. The implications of these findings are discussed
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Surface modification of mineral dust particles by sulphuric acid processing: Implications for ice nucleation abilities
The ability of coated mineral dust particles to act as ice nuclei (IN) was investigated at LACIS (Leipzig Aerosol Cloud Interaction Simulator) during the FROST1- and FROST2-campaigns (Freezing of dust). Sulphuric acid was condensed on the particles which afterwards were optionally humidified, treated with ammonia vapour and/or heat. By means of aerosol mass spectrometry we found evidence that processing of mineral dust particles with sulphuric acid leads to surface modifications of the particles. These surface modifications are most likely responsible for the observed reduction of the IN activation of the particles. The observed particle mass spectra suggest that different treatments lead to different chemical reactions on the particle surface. Possible chemical reaction pathways and products are suggested and the implications on the IN efficiency of the treated dust particles are discussed
Optical absorption spectra of finite systems from a conserving Bethe-Salpeter equation approach
We present a method for computing optical absorption spectra by means of a
Bethe-Salpeter equation approach, which is based on a conserving linear
response calculation for electron-hole coherences in the presence of an
external electromagnetic field. This procedure allows, in principle, for the
determination of the electron-hole correlation function self-consistently with
the corresponding single-particle Green function. We analyze the general
approach for a "one-shot" calculation of the photoabsorption cross section of
finite systems, and discuss the importance of scattering and dephasing
contributions in this approach. We apply the method to the closed-shell
clusters Na_4, Na^+_9 and Na^+_(21), treating one active electron per Na atom.Comment: 9 pages, 3 figure
A Single Laser System for Ground-State Cooling of 25-Mg+
We present a single solid-state laser system to cool, coherently manipulate
and detect Mg ions. Coherent manipulation is accomplished by
coupling two hyperfine ground state levels using a pair of far-detuned Raman
laser beams. Resonant light for Doppler cooling and detection is derived from
the same laser source by means of an electro-optic modulator, generating a
sideband which is resonant with the atomic transition. We demonstrate
ground-state cooling of one of the vibrational modes of the ion in the trap
using resolved-sideband cooling. The cooling performance is studied and
discussed by observing the temporal evolution of Raman-stimulated sideband
transitions. The setup is a major simplification over existing state-of-the-art
systems, typically involving up to three separate laser sources
Transcendence over Diversity: black women in the academy
Universities, like many major public institutions have embraced the notion of âdiversityâ virtually uncritically- it is seen as a moral âgood in itselfâ. But what happens to those who come to represent âdiversityâ- the black and minority ethnic groups targeted to increase the institutions thirst for global markets and aversion to accusations of institutional racism? Drawing on existing literature which analyses the process of marginalization in higher education, this paper explores the individual costs to black and female academic staff regardless of the discourse on diversity. However despite the exclusion of staff, black and minority ethnic women are also entering higher education in relatively large numbers as students. Such âgrassrootsâ educational urgency transcends the dominant discourse on diversity and challenges presumptions inherent in top down initiatives such as âwidening participationâ. Such a collective movement from the bottom up shows the importance of understanding black female agency when unpacking the complex dynamics of gendered and racialised exclusion. Black womenâs desire for education and learning makes possible a reclaiming of higher education from creeping instrumentalism and reinstates it as a radical site of resistance and refutation
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