2,765 research outputs found
Pseudopotential for the electron-electron interaction
We propose a pseudopotential for the electron-electron Coulomb interaction to
improve the efficiency of many-body electronic structure calculations. The
pseudopotential accurately replicates the scattering properties of the Coulomb
interaction, and recovers the analytical solution for two electrons in a
parabolic trap. A case study for the homogeneous electron gas using the
diffusion Monte Carlo and configuration interaction methods recovers highly
accurate values for the ground state energy, and the smoother potential reduces
the computational cost by a factor of ~30. Finally, we demonstrate the use of
the pseudopotential to study isolated lithium and beryllium atoms.GJC acknowledges the financial support of the Royal Society and Gonville & Caius College.This is the author accepted manuscript. The final version is available from APS via http://dx.doi.org/http://dx.doi.org/10.1103/PhysRevB.92.07510
Nanomedicine - nanoparticles, molecular biosensors and targeted gene/drug delivery for combined single-cell diagnostics and therapeutics
Next generation nanomedicine technologies are being developed to provide for continuous and linked molecular diagnostics and therapeutics. Research is being performed to develop "sentinel nanoparticles" which will seek out diseased (e.g. cancerous) cells, enter those living cells, and either perform repairs or induce those cells to die through apoptosis. These nanoparticles are envisioned as multifunctional "smart drug delivery systems"
Delayed reperfusion deficits after experimental stroke account for increased pathophysiology.
Cerebral blood flow and oxygenation in the first few hours after reperfusion following ischemic stroke are critical for therapeutic interventions but are not well understood. We investigate changes in oxyhemoglobin (HbO(2)) concentration in the cortex during and after ischemic stroke, using multispectral optical imaging in anesthetized mice, a remote filament to induce either 30 minute middle cerebral artery occlusion (MCAo), sham surgery or anesthesia alone. Immunohistochemistry establishes cortical injury and correlates the severity of damage with the change of oxygen perfusion. All groups were imaged for 6 hours after MCAo or sham surgery. Oxygenation maps were calculated using a pathlength scaling algorithm. The MCAo group shows a significant drop in HbO(2) during occlusion and an initial increase after reperfusion. Over the subsequent 6 hours HbO(2) concentrations decline to levels below those observed during stroke. Platelets, activated microglia, interleukin-1α, evidence of BBB breakdown and neuronal stress increase within the stroked hemisphere and correlate with the severity of the delayed reperfusion deficit but not with the ÎHbO(2) during stroke. Despite initial restoration of HbO(2) after 30 min MCAo there is a delayed compromise that coincides with inflammation and could be a target for improved stroke outcome after thrombolysis
Using multi-modal neuroimaging to characterise social brain specialisation in infants
The specialised regional functionality of the mature human cortex partly emerges
through experience-dependent specialisation during early development. Our existing understanding
of functional specialisation in the infant brain is based on evidence from unitary imaging modalities
and has thus focused on isolated estimates of spatial or temporal selectivity of neural or haemodynamic activation, giving an incomplete picture. We speculate that functional specialisation will
be underpinned by better coordinated haemodynamic and metabolic changes in a broadly orchestrated physiological response. To enable researchers to track this process through development, we
develop new tools that allow the simultaneous measurement of coordinated neural activity (EEG),
metabolic rate, and oxygenated blood supply (broadband near-infrared spectroscopy) in the awake
infant. In 4- to 7-month-old infants, we use these new tools to show that social processing is accompanied by spatially and temporally specific increases in coupled activation in the temporal-parietal
junction, a core hub region of the adult social brain. During non-social processing, coupled activation decreased in the same region, indicating specificity to social processing. Coupling was strongest
with high-frequency brain activity (beta and gamma), consistent with the greater energetic requirements and more localised action of high-frequency brain activity. The development of simultaneous
multimodal neural measures will enable future researchers to open new vistas in understanding functional specialisation of the brain
Service evaluation of weight outcomes as a function of initial BMI in 34,271 adults referred to a primary care/commercial weight management partnership scheme
Peer reviewedPublisher PD
Electromagnetic channel capacity for practical purposes
We give analytic upper bounds to the channel capacity C for transmission of
classical information in electromagnetic channels (bosonic channels with
thermal noise). In the practically relevant regimes of high noise and low
transmissivity, by comparison with know lower bounds on C, our inequalities
determine the value of the capacity up to corrections which are irrelevant for
all practical purposes. Examples of such channels are radio communication,
infrared or visible-wavelength free space channels. We also provide bounds to
active channels that include amplification.Comment: 6 pages, 3 figures. NB: the capacity bounds are constructed by
generalizing to the multi-mode case the minimum-output entropy bounds of
arXiv:quant-ph/0404005 [Phys. Rev. A 70, 032315 (2004)
Parasite control practices on Swedish horse farms
Conclusion: The results show that routines for endoparasite control can be improved in many horse establishments. To increase the knowledge of equine endoparasite control and follow the recommendations for how to reduce the spread of anthelmintic resistance, a closer collaboration between parasitologists and veterinary practitioners is desirable
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