Level Splitting in Association with the Multiphoton Bloch-Siegert Shift

We present a unitary equivalent spin-boson Hamiltonian in which terms can be identified which contribute to the Bloch-Siegert shift, and to the level splittings at the anticrossings associated with the Bloch-Siegert resonances. First-order degenerate perturbation theory is used to develop approximate results in the case of moderate coupling for the level splitting.Comment: 8 pages, 2 figure

Word finding deficitsin aphasia: diagnosis and treatment. Rotterdam Aphasia Therapy Study-2

Aphasia Imagine finding yourself all of a sudden alone in a Chinese city and not speaking or understanding Chinese. How do you ask for the way or read the signs, buy food and other necessities, watch tv or listen to the news, let alone have a social conversation with someone? This thought experiment might shed some light on how it must be for people to have a stroke and suddenly have lost the ability to communicate. The term aphasia is used to describe an acquired loss or impairment of the language system following brain damage. Damage to the brain can be caused by trauma, a tumor, infection or neurodegenerative disease such as Alzheimer’s disease. But the most frequent cause of aphasia is a stroke, mainly to the left hemisphere, where the language function of the brain is located in nearly all right-handed people and half of the left handers. In the Netherlands, approximately 40,000 people per year experience a stroke.1 About one-third of these patients develop aphasia, with higher frequencies in the early stages after stroke onset. It is estimated that there are about 30,000 people with aphasia in the Netherlands (www.afasie.nl). The severity of aphasia varies from occasional word-finding di≤culties to having no means of communication at all. Individual aphasia profiles also vary regarding the degree of involvement of the modalities of language processing: speaking, comprehension of speech, writing and reading. A central problem for nearly all aphasic people is word finding, which requires intact semantic and phonological processing. During the first year following the stroke event, aphasia tends to improve.2 A recent study found that 74% of patients presenting with aphasia in the hyperacute stage have completely recovered after six months and that aphasia improved in 86% of the patients.3 Most of the recovery occurs in the first three months after which the speed of spontaneous recovery slows, and little additional recovery can be expected after 12 months. Spontaneous recovery of cognitive functions is considered to be associated with the reduction of edema and the reperfusion of previously hypoxic tissue in the perilesional area.4 Neuroplasticity might also underlie some degree of functional recovery after stroke and has been shown to occur in perilesional areas and in areas distant from the lesion in both the acute and chronic phase.5 The most powerful

Excitation transfer in two two-level systems coupled to an oscillator

We consider a generalization of the spin-boson model in which two different two-level systems are coupled to an oscillator, under conditions where the oscillator energy is much less than the two-level system energies, and where the oscillator is highly excited. We find that the two-level system transition energy is shifted, producing a Bloch-Siegert shift in each two-level system similar to what would be obtained if the other were absent. At resonances associated with energy exchange between a two-level system and the oscillator, the level splitting is about the same as would be obtained in the spin-boson model at a Bloch-Siegert resonance. However, there occur resonances associated with the transfer of excitation between one two-level system and the other, an effect not present in the spin-boson model. We use a unitary transformation leading to a rotated system in which terms responsible for the shift and splittings can be identified. The level splittings at the anticrossings associated with both energy exchange and excitation transfer resonances are accounted for with simple two-state models and degenerate perturbation theory using operators that appear in the rotated Hamiltonian.Comment: 26 pages, 4 figure

Weak Type Inequalities for Maximal Operators Associated to Double Ergodic Sums

Given an approach region Γ ∈ Z+2 and a pair U, V of commuting nonperiodic measure preserving transformations on a probability space (Ω, Σ, μ), it is shown that either the associated multiparameter ergodic averages of any function in L1(Ω) converge a.e. or that, given a positive increasing function ϕ on [0,∞) that is o(log x) as x → ∞, there exists a function g ∈ Lϕ(L)(Ω) whose associated multiparameter ergodic averages fail to converge a.e

Intracellular mechanism of the action of inhibin on the secretion of follicular stimulating hormone and of luteinizing hormone induced by LH-RH in vitro

The FSH secretion-inhibiting action of inhibin in vitro under basal conditions and also in the presence of LH-RH is suppressed by the addition of MIX, a phosphodiesterase inhibitor. In the presence of LH-RH, inhibin reduces significantly the intracellular level of cAMP in isolated pituitary cells. In contrast, the simultaneous addition of MIX and inhibin raises the cAMP level, and this stimulation is comparable to the increase observed when MIX is added alone. These observations suggest that one mode of action of inhibin could be mediated by a reduction in cAMP within the pituitary gonadotropic cell

An Efficient Opportunistic Cooperative Diversity Protocol for IEEE 802.11 Networks

Opportunistic cooperation promises to enhance the user experience when streaming media over wireless devices by improving wireless network reliability at the link level. This paper presents DAFMAC, an efficient cooperative diversity partner selection algorithm for IEEE 802.11 devices. Simulation results show DAFMAC provides a significantly higher transmission reliability in poor channel conditions than traditional ARQ techniques without modifying the device hardware. Further analysis shows the low overhead of DAFMAC makes it highly competitive with other proposed cooperative retransmission mechanisms in an ad-hoc network

Fibrous dysplasia and the McCune-Albright syndrome: various aspects of a heterogeneous disease

In this thesis various aspects of fibrous dysplasia/the McCune-Albright syndrome (FD/MAS) are presented. Bontius Stichting; Nederlandse Vereniging voor Calcium- en BotstofwisselingLUMC / Geneeskund

Analytic Performance Model for State-Based MAC Layer Cooperative Retransmission Protocols

© 2015 IEEE. Cooperative retransmission can significantly improve link reliability over lossy and time-varying wireless links. However, comparing retransmission protocols is challenging, and generally requires simplistic assumptions specific to each protocol. In this paper, we develop a general model to evaluate cooperative retransmission protocols with distributed, slot-based contention algorithms. Specifically, we propose to calculate the relay time-out probabilities at a MAC time-slot scale, formulate retransmission outcomes as functions of the time-out probabilities, and derive the probability of a retransmission process for every data frame. We also propose a Markov extension of our model to characterise the dependency between retransmissions of multiple frames. This enables our model to analyse continuous retransmissions of successive frames. Validated by QualNet simulations, our model can analytically predict the probabilities of cooperative retransmissions with an accuracy of ± 1%. As a result, direct comparisons between cooperative retransmission protocols become tangible, without implementing the full protocol in a state-based simulator