32,210 research outputs found
United States Attorneys — Whom Shall They Serve?
Perry examines the fidelity of US Attorneys in a new light and provides a way to consider them more broadly
Study of optical properties and collective oscillations in new solid-state materials as a function of temperature using infrared and Raman techniques Semiannual report, 1 Aug. 1968 - 31 Jan. 1969
Optical properties and electronic transitions in solid crystals as function of temperature using infrared and Raman technique
Coupling a Self-Dual Tensor to Gravity in Six Dimensions
A recent result concerning interacting theories of self-dual tensor gauge
fields in six dimensions is generalized to include coupling to gravity. The
formalism makes five of the six general coordinate invariances manifest,
whereas the sixth one requires a non-trivial analysis. The result should be
helpful in formulating the world-volume action of the M theory five-brane.Comment: 7 pages, latex, no figure
Observation of high-energy vibrational overtones of molecules in solids: Local modes and intramolecular relaxations
In the last few years, the spectra of vibrational overtones (1) (at ~15-20,000 cm^-1) in large molecules have received considerable attention. The focus is on three problems dealing with the origin of relaxation at such high energies, the association of spectral band positions with the local modes (LM) in molecules, and the relevance of these spectra to possible selectivity in laser-induced chemistry
Non-BPS D8-branes and Dynamic Domain Walls in Massive IIA Supergravities
We study the D8-branes of the Romans massive IIA supergravity theory using
the coupled supergravity and worldvolume actions. D8 branes can be regarded as
domain walls with the jump in the extrinsic curvature at the brane given by the
Israel matching conditions. We examine the restrictions that these conditions
place on extreme and non-extreme solutions and find that they rule out some of
the supersymmetric solutions given by Bergshoeff {\em et al}. We consider what
happens when the dilaton varies on the worldvolume of the brane, which implies
that the brane is no longer static. We obtain a family of D8-brane solutions
parametrized by a non-extremality term on each side of the brane and the
asymptotic values of the 10-form field. The non-extremality parameters can be
related to the velocity of the brane. We also study 8-brane solutions of a
massive IIA supergravity theory introduced by Howe, Lambert and West. This
theory also admits a 10-form formulation, but the 10-form is not a R-R sector
field and so these 8-branes are not D-branes.Comment: 23 pages REVTeX, 2 .eps figures. This paper completely replaces and
extends an earlier paper (hep-th/9712112) by Chamblin and Perr
The Raman spectra of PbTiO sub 3 and solid solutions of NaTaO sub 3-KTaO sub 3 and KTaO sub 3-KNbO sub 3
Raman spectra of lead titanium trioxide and solid solutions of sodium tantalum trioxide-potassium tantalum trioxide and potassium niobium trioxid
Thermal Lensing Spectroscopy With Picosecond Pulse Trains and a New Dual Beam Configuration
In this communication, we wish to report on the use of synchronously mode-locked picosecond lasers in a pump-probe configuration for TL spectroscopy. The peak power for these picosecond lasers is very high and, of course, the fundamental of the dye laser (red beam) can be efficiently (~10%) doubled in frequency (U.V. beam) by second harmonic generation in nonlinear crystals. We use this generated U.V. beam as a probe to monitor the very weak absorption of the red beam. An arrangement [4] of the beams involving different waist positions for the pump and probe is used. This arrangement results in an enhancement of sensitivity (at least a factor of three to seven). Also, a different dependence of the signal on the cell position compared to the single beam method is obtained. Finally, we have obtained the Δν = 5 CH-stretching overtone absorption spectrum of liquid toluene with this method (see Figure 1). Suggestions are made regarding new applications of this picosecond pulse thermal lensing technique
Supplier search in industrial clusters: Sheffield metal working in the 1990s
Industrial clusters can be characterised by high levels of personal interaction between the owners/managers of firms. It has been argued that within industrial clusters community and firm tend to merge. One result of the notion of a cluster as a community is that it might be expected that personal interaction between members of the community will have an important influence on intra-cluster trading patterns. Whereas there appears to be a number of anecdotal stories of the impact of the 'personal' upon the 'economic' within clusters we do not know whether such relationships are uniquely part of cluster behaviour or whether they are found more widely within the industrial system. The paper reports the result of a new interview survey of seventy small metal working firms in the Sheffield metal working cluster in the UK. Although dealing with a traditional industrial sector the analysis is focused upon contemporary business patterns. It explores the ways in which owner/managers of small metal working firms search for new suppliers. In the empirical analysis the search process is conceptualised as being characterised by two stages: the identification of potential new suppliers and the selection of a specific new supplier. The research is in undertaken in two parts. It first measures the role of the personal networks of the owner/managers of small firms in the identification and selection of suppliers. Second, the research examines whether personal factors are more important in the identification and selection of within cluster suppliers than in the identification and selection of suppliers based outside the cluster. It is shown that, overall, personal networks are of major significance in the identification of suppliers and that information received from third parties are more important than direct contacts between the owner/manager and the potential supplier. However, in the selection decision, price and availability are dominant considerations and personal factors such as trust and reputation of only minor significance. It was not possible to identify a cluster effect in disaggregation of the data to separate out the relationships with cluster suppliers and relationships with suppliers based outside the cluster. There was no evidence that personal factors play a more important role in the establishment of within cluster links. In sum, personal networks are important in the identification of within cluster links but they are equally important in the establishment of links outside the cluster. This suggests that the importance of personal interaction within clusters has been overplayed.
Note on restoring manifest rotational symmetry in hyperfine and fine structure in light-front QED
We study the part of the renormalized, cutoff QED light-front Hamiltonian
that does not change particle number. The Hamiltonian contains interactions
that must be treated in second-order bound state perturbation theory to obtain
hyperfine structure. We show that a simple unitary transformation leads
directly to the familiar Breit-Fermi spin-spin and tensor interactions, which
can be treated in degenerate first-order bound-state perturbation theory, thus
simplifying analytic light-front QED calculations. To the order in momenta we
need to consider, this transformation is equivalent to a Melosh rotation. We
also study how the similarity transformation affects spin-orbit interactions.Comment: 17 pages, latex fil
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