603 research outputs found
On cohomological dimension and depth under linkage
Some relations between cohomological dimensions and depths of linked ideals
are investigated and discussed by various examples.Comment: 7 page
Cooling of a Nanomechanical Resonator in the Presence of a Single Diatomic Molecule
We propose a theoretical scheme for coupling a nanomechanical resonator to a
single diatomic molecule via microwave cavity mode of a driven LC resonator. We
describe the diatomic molecule by a Morse potential and find the corresponding
equations of motion of the hybrid system by using Fokker-Planck formalism.
Analytical expressions for the effective frequency and the effective damping of
the nanomechanical resonator are obtained. We analyze the ground state cooling
of the nanomechanical resonator in presence of the diatomic molecule. The
results confirm that presence of the molecule improves the cooling process of
the mechanical resonator. Finally, the effect of molecule's parameters on the
cooling mechanism is studied.Comment: 10 pages, 8 figure
Improved Energy Detector for Wideband Spectrum Sensing in Cognitive Radio Networks
In this paper, an improved energy detector for a wideband spectrum sensing is proposed. For a better detection of the spectrum holes the overall band is divided into equal non-overlapping sub-bands. The main objective is to determine the detection thresholds for each of these subbands jointly. By defining the problem as an optimization problem, we aim to find the maximum aggregated opportunistic throughput of cognitive radio networks. Introducing practical constraints to this optimization problem will change the problem into a convex and solvable one. The results of this paper show that the proposed improved energy detector will increase the aggregated throughput considerably
String cosmology from Poisson-Lie T-dual sigma models on supermanifolds
We generalize the formulation of Poisson-Lie T-dual sigma models on manifolds
to supermanifolds. In this respect, we formulate 1+1 dimensional string
cosmological models on the Lie supergroup C^3 and its dual (A_1,1 +
2A)^0_(1,0,0), which are coupled to two fermionic fields. Then, we solve the
equations of motion of the models and show that there is a essential
singularity for the metric of the original model and its dual.Comment: 17 pages, Appendix and three references have adde
Generating quantum discord between two distant Bose-Einstein condensates with Bell-like detection
We propose a technique that enables the creation of quantum discord between
two distant nodes, each containing a cavity consist of the Bose-Einstein
condensate, by applying a non-ideal Bell-like detection on the output modes of
optical cavities. We find the covariance matrix of the system after the
non-ideal Bell-like detection, showing explicitly that one enables manipulation
of the quantum correlations, and particularly quantum discord, between remote
Bose-Einstein condensates. We also find that the non-ideal Bell-like detection
can create entanglement between distant Bose-Einstein condensates at the two
remote site
Mothers’ experience of having children with diabetes
Abstract
Background: Diabetes is a major health problem, which has a wide prevalence in the world. There is no sign of its stopping, but
it is increasing. Diabetes in children is three to four times more common than other childhood diseases. Diagnosis of diabetes for
children causes emotional responses in parents and family members. Interventions for children with diabetes involve the family,
child, and professionals including physicians, nurses, and nutritionist. Self-care is difficult without direct parents’ participation.
According to studies, burden of diabetes for mothers is more than for fathers. This study aimed to explore mothers’ experience
of children with diabetes.
Materials and Methods: This is a qualitative content analysis. Study population was recruited through purposeful sampling. Eleven
mothers who have a child with diabetes and referring to the “Glands and Metabolism Research Center” and “Al-Zahra Hospital”
were selected. Participants were aged 28 to 42 years. Data gathering was done through deep interviews with participants in 2007
that was tape-recorded. Mean average of interviews was 45 minutes. Data analysis was done using conventional qualitative
content analysis.
Results: Participants’ experience was classified in the two main concepts including reaction at the time of diagnosis and disease
consequences for mothers.
Conclusion: Mothers of children with diabetes expressed some reactions at the time of diagnosis, which was mainly due to lack
of information, and lack of attention to their needs at the time of diagnosis, especially it was due to the sudden diagnosis and lack
of enough opportunities for mothers to accept the disease. The disease causes some consequences for mothers that affect their
lives. Therefore, it is necessary to consider the needs of families of children with diabetes and to provide support and sufficient
information about their child’s illness for them
Mutual information as an order parameter for quantum synchronization
Spontaneous synchronization is a fundamental phenomenon, important in many
theoretical studies and applications. Recently this effect has been analyzed
and observed in a number of physical systems close to the quantum mechanical
regime. In this work we propose the mutual information as a useful order
parameter which can capture the emergence of synchronization in very different
contexts, ranging from semi-classical to intrinsically quantum mechanical
systems. Specifically we first study the synchronization of two coupled Van der
Pol oscillators in both classical and quantum regimes and later we consider the
synchronization of two qubits inside two coupled optical cavities. In all these
contexts, we find that mutual information can be used as an appropriate figure
of merit for determining the synchronization phases, independently of the
specific details of the system
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