4,874 research outputs found
Resonance Enhanced Tunneling
Time evolution of tunneling in thermal medium is examined using the real-time
semiclassical formalism previously developed. Effect of anharmonic terms in the
potential well is shown to give a new mechanism of resonance enhanced
tunneling. If the friction from environment is small enough, this mechanism may
give a very large enhancement for the tunneling rate. The case of the
asymmetric wine bottle potential is worked out in detail.Comment: 12 pages, LATEX file with 5 PS figure
Particle creation in an oscillating spherical cavity
We study the creation of massless scalar particles from the quantum vacuum
due to the dynamical Casimir effect by spherical shell with oscillating radius.
In the case of a small amplitude of the oscillation, to solve the infinite set
of coupled differential equations for the instantaneous basis expansion
coefficients we use the method based on the time-dependent perturbation theory
of the quantum mechanics. To the first order of the amplitude we derive the
expressions for the number of the created particles for both parametric
resonance and non-resonance cases.Comment: 8 pages, LaTeX, no figure
Quantum Dissipation and Decay in Medium
Quantum dissipation in thermal environment is investigated, using the path
integral approach. The reduced density matrix of the harmonic oscillator system
coupled to thermal bath of oscillators is derived for arbitrary spectrum of
bath oscillators. Time evolution and the end point of two-body decay of
unstable particles is then elucidated: After early transient times unstable
particles undergo the exponential decay, followed by the power law decay and
finally ending in a mixed state of residual particles containing contributions
from both on and off the mass shell, whose abundance does not suffer from the
Boltzmann suppression.Comment: 19 pages, LATEX file. Substantially expanded and revised for
publication, including more complete description of application to unstable
particle decay in thermal medium. Some minor mistake of numerical factors
correcte
Patient perspective on decisions to switch disease-modifying treatments in relapsing-remitting multiple sclerosis
Background: There are now large cohorts of people with relapsing-remitting multiple sclerosis (pwRRMS) who have taken several Disease-Modifying Treatments (DMTs). Studies about switching DMTs mostly focus on clinical outcomes rather than patients' decision-making. Neurologists are now required to support decisions at various times during the relapsing disease course and they do so with concerns about DMTs risks. This qualitative study investigates how pwRRMS weigh up the pros and cons of DMTs, focusing on perceptions of effectiveness and risks when new treatments are considered. /
Objective: To increase understanding of people's experiences of decision-making when switching DMTs. /
Methods: 30 semi-structured interviews were conducted with pwRRMS in England. 16 participants had switched DMT and their experiences were compared with those who had only taken one DMT. Interviews were analysed thematically to answer: what main factors influence people's decision-making to switch DMTs and why? /
Results: Of the 16 participants with experience of switching DMT, eight had taken two or more DMTs; eight had taken three or more. Two was the DMT median. This study demonstrated that despite the term "switching" implying that similar treatments are inter-changeable, for pwRRMS taking new treatments involves different emotions, routines, risks, prognosis and communication experiences. Two meta themes identified were: 1) A distinctive, rapid and emotional decision-making process where old emotions related to MS prognosis are revisited. 2) Switching has a different impact on communication for escalation or de-escalation processes. /
Conclusion: Switching DMT involves different routines, risks, prognosis and communication experiences. These decisions are emotionally difficult because of the fear about transitioning to secondary progressive MS, and DMT effectiveness uncertainty. Patient centred decision aids should include information about first and consecutive treatment decisions
Dynamics of barrier penetration in thermal medium: exact result for inverted harmonic oscillator
Time evolution of quantum tunneling is studied when the tunneling system is
immersed in thermal medium. We analyze in detail the behavior of the system
after integrating out the environment. Exact result for the inverted harmonic
oscillator of the tunneling potential is derived and the barrier penetration
factor is explicitly worked out as a function of time. Quantum mechanical
formula without environment is modifed both by the potential renormalization
effect and by a dynamical factor which may appreciably differ from the
previously obtained one in the time range of 1/(curvature at the top of
potential barrier).Comment: 30 pages, LATEX file with 11 PS figure
Adolescentsâ responses to the promotion and flavouring of e-cigarettes
Objectives
The purpose of the study is to examine adolescentsâ awareness of e-cigarette marketing and investigate the impact of e-cigarette flavour descriptors on perceptions of product harm and user image.
Methods
Data come from the 2014 Youth Tobacco Policy Survey, a cross-sectional in-home survey conducted with 11â16 year olds across the UK (n = 1205). Adolescentsâ awareness of e-cigarette promotion, brands, and flavours was assessed. Perceptions of product harm, and likely user of four examples of e-cigarette flavours was also examined.
Results
Some participants had tried e-cigarettes (12 %) but regular use was low (2 %) and confined to adolescents who had also smoked tobacco. Most were aware of at least one promotional channel (82 %) and that e-cigarettes came in different flavours (69 %). Brand awareness was low. E-cigarettes were perceived as harmful (M = 3.54, SD = 1.19) but this was moderated by product flavours. Fruit and sweet flavours were perceived as more likely to be tried by young never smokers than adult smokers trying to quit (p < 0.001).
Conclusions
There is a need to monitor the impact of future market and regulatory change on youth uptake and perceptions of e-cigarettes
Squeezing of Atoms in a Pulsed Optical Lattice
We study the process of squeezing of an ensemble of cold atoms in a pulsed
optical lattice. The problem is treated both classically and
quantum-mechanically under various thermal conditions. We show that a dramatic
compression of the atomic density near the minima of the optical potential can
be achieved with a proper pulsing of the lattice. Several strategies leading to
the enhanced atomic squeezing are suggested, compared and optimized.Comment: Latex, 9 pages, 10 figures, submitted to PR
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Seeking and accessing professional support for child anxiety in a community sample
There is a lack of current data on help-seeking, and barriers to accessing professional support for child anxiety disorders. This study aimed to provide current data on the frequency and type of parental help-seeking, professional support received, and parent-reported barriers/facilitators in the context of child anxiety, and to explore factors associated with help-seeking, and parent-reported barriers among help-seekers and non help-seekers. We conducted a survey of help-seeking in parents of 222 children (aged 7-11) with elevated anxiety symptoms identified through screening in schools, 138 children of whom met diagnostic criteria for an anxiety disorder. Almost two-thirds (64.5%) of parents of children with an anxiety disorder reported seeking help from a professional; in 38.4% of cases parents reported that their child had received support from a professional to help manage and overcome their anxiety difficulties, andâ<â3% had received evidence-based treatment (CBT). Frequently reported parental barriers related to difficulties differentiating between developmentally appropriate and clinically significant anxiety, a lack of help-seeking knowledge, perceived negative consequences of help-seeking, and limited service provision. Non-help seekers were more likely than help seekers to report barriers related to thinking a child's anxiety may improve without professional support, and the absence of professional recognition. Findings identify the need for (i) tools for parents and primary school staff to help identify children who may benefit from professional support to overcome difficulties with anxiety; and (ii) increased evidence-based provision for child anxiety disorders, including delivery within schools and direct support for parents
Poly(ADP-ribose) polymerase family member 14 (PARP14) is a novel effector of the JNK2-dependent pro-survival signal in multiple myeloma
Copyright @ 2013 Macmillan Publishers Limited. This is the author's accepted manuscript. The final published article is available from the link below.Regulation of cell survival is a key part of the pathogenesis of multiple myeloma (MM). Jun N-terminal kinase (JNK) signaling has been implicated in MM pathogenesis, but its function is unclear. To elucidate the role of JNK in MM, we evaluated the specific functions of the two major JNK proteins, JNK1 and JNK2. We show here that JNK2 is constitutively activated in a panel of MM cell lines and primary tumors. Using loss-of-function studies, we demonstrate that JNK2 is required for the survival of myeloma cells and constitutively suppresses JNK1-mediated apoptosis by affecting expression of poly(ADP-ribose) polymerase (PARP)14, a key regulator of B-cell survival. Strikingly, we found that PARP14 is highly expressed in myeloma plasma cells and associated with disease progression and poor survival. Overexpression of PARP14 completely rescued myeloma cells from apoptosis induced by JNK2 knockdown, indicating that PARP14 is critically involved in JNK2-dependent survival. Mechanistically, PARP14 was found to promote the survival of myeloma cells by binding and inhibiting JNK1. Moreover, inhibition of PARP14 enhances the sensitization of MM cells to anti-myeloma agents. Our findings reveal a novel regulatory pathway in myeloma cells through which JNK2 signals cell survival via PARP14, and identify PARP14 as a potential therapeutic target in myeloma.Kay Kendall Leukemia Fund, NIH, Cancer Research UK, Italian Association for Cancer Research and the Foundation for Liver Research
Ergodic properties of quasi-Markovian generalized Langevin equations with configuration dependent noise and non-conservative force
We discuss the ergodic properties of quasi-Markovian stochastic differential
equations, providing general conditions that ensure existence and uniqueness of
a smooth invariant distribution and exponential convergence of the evolution
operator in suitably weighted spaces, which implies the validity
of central limit theorem for the respective solution processes. The main new
result is an ergodicity condition for the generalized Langevin equation with
configuration-dependent noise and (non-)conservative force
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