48 research outputs found
Comparison of two non-primitive methods for path integral simulations: Higher-order corrections vs. an effective propagator approach
Two methods are compared that are used in path integral simulations. Both
methods aim to achieve faster convergence to the quantum limit than the
so-called primitive algorithm (PA). One method, originally proposed by
Takahashi and Imada, is based on a higher-order approximation (HOA) of the
quantum mechanical density operator. The other method is based upon an
effective propagator (EPr). This propagator is constructed such that it
produces correctly one and two-particle imaginary time correlation functions in
the limit of small densities even for finite Trotter numbers P. We discuss the
conceptual differences between both methods and compare the convergence rate of
both approaches. While the HOA method converges faster than the EPr approach,
EPr gives surprisingly good estimates of thermal quantities already for P = 1.
Despite a significant improvement with respect to PA, neither HOA nor EPr
overcomes the need to increase P linearly with inverse temperature. We also
derive the proper estimator for radial distribution functions for HOA based
path integral simulations.Comment: 17 pages, latex, 6 postscript figure
Graphene transistors are insensitive to pH changes in solution
We observe very small gate-voltage shifts in the transfer characteristic of
as-prepared graphene field-effect transistors (GFETs) when the pH of the buffer
is changed. This observation is in strong contrast to Si-based ion-sensitive
FETs. The low gate-shift of a GFET can be further reduced if the graphene
surface is covered with a hydrophobic fluorobenzene layer. If a thin Al-oxide
layer is applied instead, the opposite happens. This suggests that clean
graphene does not sense the chemical potential of protons. A GFET can therefore
be used as a reference electrode in an aqueous electrolyte. Our finding sheds
light on the large variety of pH-induced gate shifts that have been published
for GFETs in the recent literature
Lending Crowdfunding : Principles and Market Development
publishedVersio
Queer Touch Between Holy Women: Julian of Norwich, Margery Kempe, Birgitta of Sweden, and the Visitation
Under embargo until: 2021-12-17This essay takes a new approach to the well-known meeting between two late-medieval English visionary women, Margery Kempe and the anchoress Julian of Norwich, as described in The Book of Margery Kempe. In this analysis their conversation subtly evokes a long history of women concentrating their subversive power through intimate, spiritual exchange, a history reaching back to the Biblical Visitation scene and expressed in its medieval artistic and literary instantiations. A queer reading illuminates the way that such female same-sex relationships challenge patriarchal systems by offering a privileged access to God outside clerical supervision. By examining Margery and Julian’s encounter, Luke’s Visitation passage, its depiction in a late-medieval Book of Hours, and comparing two different Middle English translations of a Visitation vision in Birgitta of Sweden’s Revelations, the full transgressive effect of queer touch between women—or even its unspoken possibility—emerges.acceptedVersio
How Common is Common Human Reason?:The Plurality of Moral Perspectives and Kant’s Ethics
In his practical philosophy, Kant aims to systematize and ground a conception of morality that every human being already in some form is supposedly committed to in virtue of her common human reason. While Kantians especially in the last few years have explicitly acknowledged the central role of common human reason for a correct understanding of Kant’s ethics, there has been very little detailed critical discussion of the very notion of a common human reason as Kant envisages it. Sticker critically discusses in what ways Kant is committed to the notion that there are certain rational insights and rational capacities that all humans share, and thus investigates critically how Kant thinks moral normativity appears to the common human being, the rational agent who did not enjoy special education or philosophical training
The Choice between Formal and Informal Intellectual Property: A Review
We survey the economic literature, both theoretical and empirical, on the choice of intellectual property protection by firms. Our focus is on the trade-offs between using patents and disclosing versus the use of secrecy, although we also look briefly at the use of other means of formal intellectual property protection. (JEL D82, K11, O31, O34) </jats:p