128 research outputs found
Quantum random walks without walking
Quantum random walks have received much interest due to their non-intuitive
dynamics, which may hold the key to a new generation of quantum algorithms.
What remains a major challenge is a physical realization that is experimentally
viable and not limited to special connectivity criteria. We present a scheme
for walking on arbitrarily complex graphs, which can be realized using a
variety of quantum systems such as a BEC trapped inside an optical lattice.
This scheme is particularly elegant since the walker is not required to
physically step between the nodes; only flipping coins is sufficient.Comment: 12 manuscript pages, 3 figure
Detection and Molecular Characterization of Cryptosporidium species in Recreational Waters of Chaharmahal va Bakhtiyari Province of Iran using nested-PCR-RFLP
Background: The aim of this study was to detect and characterize Cryptosporidium spp. in water samples collected from recreational ponds of Chaharmahal va Bakhtiyari Province of Iran .Methods: Thirty water samples were collected from November 2009 to May 2010. Each sample contained 10 liters of water. We used the SSU rRNA-based PCR-RFLP technique.Results: Out of thirty samples examined, 6 (20%) were positive for different Cryptosporidium spp. Restriction pattern analysis showed that C. parvum has been the most prevalent genotype, followed by C. hominis and C. canis , respectively. In this area, the higher prevalence of C. parvum compared with other genotypes is consistent with the distribution of cattle.Conclusion: Farm animals, particularly cattle are the main source of cryptosporidial contamination for recreational waters in this area
Solid State Implementation of Quantum Random Walks on General Graphs
Advances in recent years have made it possible to explore quantum dots as a
viable technology for scalable quantum information processing. Charge qubits
for example can be realized in the lowest bound states of coupled quantum dots
and the precision control of the confinement potential allows for the
realization of a full set of universal qubit gates, including arbitrary
single-qubit rotations and two-qubit C-NOT gates. In this work we describe a
novel scheme for implementing quantum random walks on arbitrarily complex
graphs by extending these elementary operations to the control of a
two-dimensional quantum dot grid. As single-qubit rotations constitute the
essential building blocks of our implementation scheme, we also present
numerical simulations of one such mechanism by directly solving the
corresponding time-dependent Schrodinger equation.Comment: 6 manuscript pages, 6 figures, to appear in the proceedings of the
2nd International Workshop on Solid-State Quantum Computing and the
Mini-School on Quantum Information Scienc
Asymptotic properties of the Dirac quantum cellular automaton
We show that the Dirac quantum cellular automaton [A. Bisio, G. M. D'Ariano, and A. Tosini, Ann. Phys. (N. Y.) 354, 244 (2015)] shares many properties in common with the discrete-time quantum walk. These similarities can be exploited to study the automaton as a unitary process that takes place at regular time steps on a one-dimensional lattice, in the spirit of general quantum cellular automata. In this way, it becomes an alternative to the quantum walk, with a dispersion relation that can be controlled by a parameter that plays a similar role to the coin angle in the quantum walk. The Dirac Hamiltonian is recovered under a suitable limit. We provide two independent analytical approximations to the long-term probability distribution. It is shown that, starting from localized conditions, the asymptotic value of the entropy of entanglement between internal and motional degrees of freedom overcomes the known limit that is approached by the quantum walk for the same initial conditions and is similar to the ones achieved by highly localized states of the Dirac equation
Sensorimotor plasticity after spinal cord injury: a longitudinal and translational study
Objective
The objective was to track and compare the progression of neuroplastic changes in a large animal model and humans with spinal cord injury.
Methods
A total of 37 individuals with acute traumatic spinal cord injury were followed over time (1, 3, 6, and 12 months post-injury) with repeated neurophysiological assessments. Somatosensory and motor evoked potentials were recorded in the upper extremities above the level of injury. In a reverse-translational approach, similar neurophysiological techniques were examined in a porcine model of thoracic spinal cord injury. Twelve Yucatan mini-pigs underwent a contusive spinal cord injury at T10 and tracked with somatosensory and motor evoked potentials assessments in the fore- and hind limbs pre- (baseline, post-laminectomy) and post-injury (10 min, 3 h, 12 weeks).
Results
In both humans and pigs, the sensory responses in the cranial coordinates of upper extremities/forelimbs progressively increased from immediately post-injury to later time points. Motor responses in the forelimbs increased immediately after experimental injury in pigs, remaining elevated at 12 weeks. In humans, motor evoked potentials were significantly higher at 1-month (and remained so at 1 year) compared to normative values.
Conclusions
Despite notable differences between experimental models and the human condition, the brain's response to spinal cord injury is remarkably similar between humans and pigs. Our findings further underscore the utility of this large animal model in translational spinal cord injury research
Competency of Anopheles stephensi mysorensis strain for Plasmodium vivax and the role of inhibitory carbohydrates to block its sporogonic cycle
<p>Abstract</p> <p>Background</p> <p>Despite the abundance of studies conducted on the role of mosquitoes in malaria transmission, the biology and interaction of <it>Plasmodium </it>with its insect host still holds many mysteries. This paper provides the first study to follow the sporogonic cycle of <it>Plasmodium vivax </it>in a wild insecticide-resistant mysorensis strain of <it>Anopheles stephensi</it>, a major vector of vivax malaria in south-eastern Iran. The study subsequently demonstrates that host-parasite sugar binding interactions are critical to the development of this parasite in the salivary glands of its mosquito host. The identity of the receptors or sugars involved was revealed by a receptor "pre-saturation" strategy in which sugars fed to the mosquitoes inhibited normal host-parasite interactions.</p> <p>Methods</p> <p><it>Anopheles stephensi </it>mysorensis mosquitoes were artificially infected with <it>P. vivax </it>by feeding on the blood of gametocytaemic volunteers reporting to local malaria clinics in the Sistan-Baluchistan province of south-eastern Iran. In order to determine the inhibitory effect of carbohydrates on sporogonic development, vector mosquitoes were allowed to ingest blood meals containing both gametocytes and added carbohydrates. The carbohydrates tested were GlcNAc, GalNAc, arabinose, fucose, mannose, lactose, glucose and galactose. Sporogonic development was assessed by survival of the parasite at both the oocyst and sporozoite stages.</p> <p>Results</p> <p>Oocyst development was observed among nearly 6% of the fed control mosquitoes but the overall number of mosquitoes exhibiting sporozoite invasion of the salivary glands was 47.5% lower than the number supporting oocysts in their midgut. Of the tested carbohydrates, only arabinose and fucose slightly perturbed the development of <it>P. vivax </it>oocysts at the basal side of the mosquito midgut, and the remaining sugars caused no reductions in oocyst development. Strikingly however, sporozoites were completely absent from the salivary glands of mosquitoes treated with mannose, GalNAc, and lactose.</p> <p>Conclusion</p> <p>The study indicates that <it>An. stephensi </it>in southern Iran has the potential to survive long enough to be re-infected and transmit vivax malaria several times, based on the average adult female longevity (about 30 days) and its gonotrophic cycle (2–3 days) during the malaria transmission season. Certain sugar binding interactions are important for the development of <it>P. vivax </it>sporozoites, and this information may be instrumental for the development of transmission blocking strategies.</p
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