6,062 research outputs found
Water and the Biology of Prions and Plaques
This is an attempt to account for the insolubility and/or aggregation of prions and plaques in terms of a model of water consisting of an equilibrium between high 
density and low density microdomains. Hydrophobic molecules, including proteins, 
accumulate selectively into stable populations, enriched in high density water, at 
charged sites on biopolymers. In enriched high density water, proteins are probably 
partially unfolded and may precipitate out when released. All extracellular matrices 
contain such charged polymers. Prions, which have been shown to accumulate in soils 
and clays containing silicates and aluminates also probably accumulate in 
extracellular matrices. 
 
Release of proteins follows hydrolysis of the charged groups by highly reactive high 
density water. This is normally a slow process but is greatly accelerated by urea. 
Plaques may form with age and disease because of accumulation of urea and, perhaps, 
glucose in the blood. This favours precipitation of proteins emerging from matrices, 
rather than refolding and solution. Dialysis should, therefore, interfere with plaque 
formation and impede the development of some age-related diseases
A wireless ultrasonic NDT sensor system
Ultrasonic condition monitoring technologies have been traditionally utilized in industrial and construction environments where structural integrity is of concern. Such techniques include active systems with either single or multiple transmit-receiver combinations used to obtain defect positioning and magnitude. Active sensors are implemented in two ways; in a thickness operation mode, or as an area-mapping tool operating over longer distances. In addition, passive ultrasonic receivers can be employed to detect and record acoustic emission activity. Existing equipment requires cabling for such systems leading to expensive, complicated installations. This work describes the development and operation of a system that combines these existing ultrasonic technologies with modern wireless techniques within a miniaturized, battery-operated design. A completely wireless sensor has been designed that can independently record and analyze ultrasonic signals. Integrated into the sensor are custom ultrasonic transducers, associated analogue drive and receive electronics, and a Texas Instruments Digital Signal Processor (DSP) used to both control the system and implement the signal processing routines. BlueTooth wireless communication is used for connection to a central observation station, from where network operation can be controlled. Extending battery life is of prime importance and the device employs several strategies to do this. Low voltage transducer excitation suffers from poor signal-to-noise ratios, which can be enhanced by signal processing routines implemented on the DSP. Routines investigated include averaging, digital filtering and pulse compression
Adiabatic optical entanglement between electron spins in separate quantum dots
We present an adiabatic approach to the design of entangling quantum
operations with two electron spins localized in separate InAs/GaAs quantum dots
via the Coulomb interaction between optically-excited localized states.
Slowly-varying optical pulses minimize the pulse noise and the relaxation of
the excited states. An analytic "dressed state" solution gives a clear physical
picture of the entangling process, and a numerical solution is used to
investigate the error dynamics. For two vertically-stacked quantum dots we show
that, for a broad range of dot parameters, a two-spin state with concurrence
can be obtained by four optical pulses with durations
ns.Comment: 7 pages, 5 figure
Studies on Tropolones
Nitration of tropolone yields a mixture of alpha- and gamma-mononitrotropolones which are oriented by isomerisation, via their methyl ethers, to o- and p-nitrobenzoic acids respectively. Of the derived amino-tropolones the gamma-isomer is also produced by reduction of tropolone coupling-products and is convertible into gamma-hydroxy-, gamma-halogeno-and gamma-cyanotropolone: it also undergoes the Skraup reaction. On the other hand, diazotisation of alpha-amino-tropolone yields much salicylic acid. Nitration of alpha-bromotropolone yields the gamma-nitro-derivative. gamma-Cyanotropolone is used to prepare gamma-carboxy-tropolone and gamma-aminomethyltropolone. alpha-Carboxytropolone is synthesised via a condensate of pimelic and oxalic esters. This condensate is proved by its reactions to be 1:4-dicarbethoxycyclohepta-2:3-dione and on bromination-debydrobromination, it affords alphaalpha'-dibromotropolone. The conversion of tropolones into chlorotropones is described and halogen mobility in these compounds and in halogenotropolones is examined with especial reference to mercaptide reagents which, in most cases, can exhaustively replace the halogen substituents. Some incidental rearrangements are noted. The Interaction of ethyl oxalate and di-beta-cyanoethyl sulphide - examined in course of preliminary experiments on the synthesis of heterocyclic analogues of tropolone - leads to a sulphur-free compound which is identified, by hydrolysis and degradation, as 3:6-dicyanocatechol
Enhancement by cytotoxic agents of artificial pulmonary metastasis.
The formation of lung colonies by i.v. injected Lewis lung-tumour cells in syngeneic recipients was greatly enhanced by prior treatment of the mice with cyclophosphamide. The lung-cloning efficiency was linearly related to cyclophosphamide dose and the optimum time of treatment was 2-4 days before the injection of tumour cells. The resulting lung colonies had a similar size distribution to colonies in untreated recipients. Bleomycin, local thoraric irradiation and whole-body irradiation were much less effective in enhancing the lung-cloning efficiency. Cyclophosphamide also enhanced the take probability of i.m. implanted tumour cells
Generation of frequency sidebands on single photons with indistinguishability from quantum dots
Generation and manipulation of the quantum state of a single photon is at the
heart of many quantum information protocols. There has been growing interest in
using phase modulators as quantum optics devices that preserve coherence. In
this Letter, we have used an electro-optic phase modulator to shape the state
vector of single photons emitted by a quantum dot to generate new frequency
components (modes) and explicitly demonstrate that the phase modulation process
agrees with the theoretical prediction at a single photon level. Through
two-photon interference measurements we show that for an output consisting of
three modes (the original mode and two sidebands), the indistinguishability of
the mode engineered photon, measured through the secondorder intensity
correlation (g2(0)) is preserved. This work demonstrates a robust means to
generate a photonic qubit or more complex state (e.g., a qutrit) for quantum
communication applications by encoding information in the sidebands without the
loss of coherence
Molecular optomechanics in the anharmonic regime: from nonclassical mechanical states to mechanical lasing
Cavity optomechanics aims to establish optical control over vibrations of
mechanical systems, to heat, cool or to drive them toward coherent, or
nonclassical states. This field was recently extended to include molecular
optomechanics, which describes the dynamics of THz molecular vibrations coupled
to the optical fields of lossy cavities via Raman transitions, and was
developed to understand the anomalous amplification of optical phonons in
Surface-Enhanced Raman Scattering experiments. But the molecular platform
should prove suitable for demonstrating more sophisticated optomechanical
effects, including engineering of nonclassical mechanical states, or inducing
coherent molecular vibrations. In this work, we propose two pathways towards
implementing these effects, enabled or revealed by the strong intrinsic
anharmonicities of molecular vibrations. First, to prepare a nonclassical
mechanical state, we propose an incoherent analogue of the mechanical blockade,
in which the molecular aharmonicity and optical response of hybrid cavities
isolate the two lowest-energy vibrational states. Secondly, we show that for a
strongly driven optomechanical system, the anharmonicity can effectively
suppress the mechanical amplification, shifting and reshaping the onset of
coherent mechanical oscillations. Our estimates indicate that both effects
should be within reach of the existing implementations of the Surface Enhanced
Raman Scattering, opening the pathway towards the coherent and nonclassical
effects in molecular optomechanics
Establishing an international research collaborative for naturopathy: The International Research Consortium of Naturopathic Academic Clinics (IRCNAC)
© 2017 Elsevier Ltd Naturopathy is a system of healthcare through which practitioners apply core philosophies, theories and principles to integrate medical knowledge with natural treatment options. In recent years the naturopathic community has developed a stronger international coherence. Alongside this growing connectivity in the global naturopathic profession, there have been a number of calls for more systematic research attention to be devoted to naturopathy as a substantive research topic, as well as a need for the naturopathic profession to hone a culture of research and evidence-based practices and skillsets. Progress in this area has been made through the development of more pragmatic and whole systems naturopathic research. One aspect which is currently missing in the global naturopathic research landscape despite this growing pattern of practice-based, whole systems research is the application of international multicentre research projects. In response, we have established a research consortium for naturopathic academic clinics in four countries and across multiple world regions. This paper serves to overview the mission, scope and membership of the research consortium and explore some of the research designs and questions which it may support
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