936 research outputs found
Inverse problems with partial data for a magnetic Schr\"odinger operator in an infinite slab and on a bounded domain
In this paper we study inverse boundary value problems with partial data for
the magnetic Schr\"odinger operator. In the case of an infinite slab in ,
, we establish that the magnetic field and the electric potential can
be determined uniquely, when the Dirichlet and Neumann data are given either on
the different boundary hyperplanes of the slab or on the same hyperplane. This
is a generalization of the results of [41], obtained for the Schr\"odinger
operator without magnetic potentials. In the case of a bounded domain in ,
, extending the results of [2], we show the unique determination of the
magnetic field and electric potential from the Dirichlet and Neumann data,
given on two arbitrary open subsets of the boundary, provided that the magnetic
and electric potentials are known in a neighborhood of the boundary.
Generalizing the results of [31], we also obtain uniqueness results for the
magnetic Schr\"odinger operator, when the Dirichlet and Neumann data are known
on the same part of the boundary, assuming that the inaccessible part of the
boundary is a part of a hyperplane
Full-wave invisibility of active devices at all frequencies
There has recently been considerable interest in the possibility, both
theoretical and practical, of invisibility (or "cloaking") from observation by
electromagnetic (EM) waves. Here, we prove invisibility, with respect to
solutions of the Helmholtz and Maxwell's equations, for several constructions
of cloaking devices. Previous results have either been on the level of ray
tracing [Le,PSS] or at zero frequency [GLU2,GLU3], but recent numerical [CPSSP]
and experimental [SMJCPSS] work has provided evidence for invisibility at
frequency . We give two basic constructions for cloaking a region
contained in a domain from measurements of Cauchy data of waves at \p
\Omega; we pay particular attention to cloaking not just a passive object, but
an active device within , interpreted as a collection of sources and sinks
or an internal current.Comment: Final revision; to appear in Commun. in Math. Physic
A rigorous analysis of high order electromagnetic invisibility cloaks
There is currently a great deal of interest in the invisibility cloaks
recently proposed by Pendry et al. that are based in the transformation
approach. They obtained their results using first order transformations. In
recent papers Hendi et al. and Cai et al. considered invisibility cloaks with
high order transformations. In this paper we study high order electromagnetic
invisibility cloaks in transformation media obtained by high order
transformations from general anisotropic media. We consider the case where
there is a finite number of spherical cloaks located in different points in
space. We prove that for any incident plane wave, at any frequency, the
scattered wave is identically zero. We also consider the scattering of finite
energy wave packets. We prove that the scattering matrix is the identity, i.e.,
that for any incoming wave packet the outgoing wave packet is the same as the
incoming one. This proves that the invisibility cloaks can not be detected in
any scattering experiment with electromagnetic waves in high order
transformation media, and in particular in the first order transformation media
of Pendry et al. We also prove that the high order invisibility cloaks, as well
as the first order ones, cloak passive and active devices. The cloaked objects
completely decouple from the exterior. Actually, the cloaking outside is
independent of what is inside the cloaked objects. The electromagnetic waves
inside the cloaked objects can not leave the concealed regions and viceversa,
the electromagnetic waves outside the cloaked objects can not go inside the
concealed regions. As we prove our results for media that are obtained by
transformation from general anisotropic materials, we prove that it is possible
to cloak objects inside general crystals.Comment: The final version is now published in Journal of Physics A:
Mathematical and Theoretical, vol 41 (2008) 065207 (21 pp). Included in
IOP-Selec
Submission in Response to the Australian Productivity Commission's Inquiry into IP Arrangements Draft Report
This Submission by nine intellectual property academics responds to the Draft Report in the Inquiry into IP Arrangements published by the Australian Productivity Commission on 29 April 2016 ('Draft Report'). In broad terms, the submission supports many of the goals of, and recommendations of, the Productivity Commission expressed in the Draft Report, but expresses concerns that some recommendations may not achieve the overall goals of the Commission, or reflect misunderstandings of the statutory framework. The submission addresses many of the Commission's draft recommendations concerning copyright, patents, trade marks and geographical indicators, IP and public institutions, and IP's institutional and governance arrangements
Existential Communication and Leadership
The aim of this article is to introduce and explain a number of important existentialist philosophers and concepts that we believe can contribute to a critical approach to leadership theory. Emphasis is placed on understanding the nature of communication from an existentialist perspective and so Jaspers' conceptualization of existential communication is introduced along with important related concepts that may be regarded as important facets of leader communication including Being-in-the-world, the Other, intersubjectivity, dialogue and indirect communication. Particular attention is paid to Buber's ideas on communication as relationship and dialogue. Throughout, reference is made to contemporary, and what is often regarded as orthodox, thinking regarding the centrality of communication to leadership practice as a means by which to highlight the salience of an existentialist analysis
Understanding Face and Shame: A Servant-Leadership and Face Management Model
Clergy can have a negative impact on churches and other individuals when they knowingly or unknowingly attempt to save face, that is, try to protect their standing or reputation. The desire to gain face and the fear of losing face and feeling ashamed will likely permeate clergyâs decision-making processes without even being noticed. This study explores the essence of face and face management and the relationship between face management and two characteristics of servant-leadershipâawareness and healingâin both Chinese and American churches through the methodology of hermeneutic phenomenology. Prior to this study, to my knowledge, no hermeneutic phenomenological research of face management has been conducted in a church setting. Through a review of the literature, four areas are explored: face and shame, face management, servant-leadership, and face, shame, and face management within the church. This study obtained approval from the Institutional Review Board and informed consent from the participants. Three Chinese and three American Christian ministers were chosen to complete a question sheet and participate in two semi-structured interview sessions. A first cycle of open coding and second cycle of pattern coding were used during data analysis. Face experiences are discussed in light of eight major themes: body, triggers, becoming, face concepts, strategies, emotions, servant-leadership, and the church. Findings from the study help build a servant-leadership and face management model, which can offer an anchored approach for clergy and pastoral counselors to address face and shame and to develop therapeutic interventions
The Boundary Conditions for Point Transformed Electromagnetic Invisibility Cloaks
In this paper we study point transformed electromagnetic invisibility cloaks
in transformation media that are obtained by transformation from general
anisotropic media. We assume that there are several cloaks located in different
points in space. Our results apply in particular to the first order
invisibility cloaks introduced by Pendry et al. and to the high order
invisibility cloaks introduced by Hendi et al. and by Cai et al.. We identify
the appropriate {\it cloaking boundary conditions} that the solutions of
Maxwell equations have to satisfy at the outside, , and at the
inside, , of the boundary of the cloaked object . Namely, that
the tangential components of the electric and the magnetic fields have to
vanish at -what is always true- and that the normal components
of the curl of the electric and the magnetic fields have to vanish at . These results are proven requiring that energy be conserved. In the case
of one spherical cloak with a spherically stratified and a radial current
at we verify by an explicit calculation that our {\it cloaking
boundary conditions} are satisfied and that cloaking of active devices holds
even if the current is at the boundary of the cloaked object. As we prove our
results for media that are obtained by transformation from general anisotropic
media, our results apply to the cloaking of objects with active and passive
devices contained in general anisotropic media, in particular to objects with
active and passive devices contained inside general crystals.Comment: This final, published, version has been edited, comments have been
adde
Biological measurement beyond the quantum limit
Quantum noise places a fundamental limit on the per photon sensitivity
attainable in optical measurements. This limit is of particular importance in
biological measurements, where the optical power must be constrained to avoid
damage to the specimen. By using non-classically correlated light, we
demonstrated that the quantum limit can be surpassed in biological
measurements. Quantum enhanced microrheology was performed within yeast cells
by tracking naturally occurring lipid granules with sensitivity 2.4 dB beyond
the quantum noise limit. The viscoelastic properties of the cytoplasm could
thereby be determined with a 64% improved measurement rate. This demonstration
paves the way to apply quantum resources broadly in a biological context
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