2,261 research outputs found
Failure of Delayed Feedback Deep Brain Stimulation for Intermittent Pathological Synchronization in Parkinson's Disease
Suppression of excessively synchronous beta-band oscillatory activity in the
brain is believed to suppress hypokinetic motor symptoms of Parkinson's
disease. Recently, a lot of interest has been devoted to desynchronizing
delayed feedback deep brain stimulation (DBS). This type of synchrony control
was shown to destabilize the synchronized state in networks of simple model
oscillators as well as in networks of coupled model neurons. However, the
dynamics of the neural activity in Parkinson's disease exhibits complex
intermittent synchronous patterns, far from the idealized synchronous dynamics
used to study the delayed feedback stimulation. This study explores the action
of delayed feedback stimulation on partially synchronized oscillatory dynamics,
similar to what one observes experimentally in parkinsonian patients. We employ
a model of the basal ganglia networks which reproduces experimentally observed
fine temporal structure of the synchronous dynamics. When the parameters of our
model are such that the synchrony is unphysiologically strong, the feedback
exerts a desynchronizing action. However, when the network is tuned to
reproduce the highly variable temporal patterns observed experimentally, the
same kind of delayed feedback may actually increase the synchrony. As network
parameters are changed from the range which produces complete synchrony to
those favoring less synchronous dynamics, desynchronizing delayed feedback may
gradually turn into synchronizing stimulation. This suggests that delayed
feedback DBS in Parkinson's disease may boost rather than suppress
synchronization and is unlikely to be clinically successful. The study also
indicates that delayed feedback stimulation may not necessarily exhibit a
desynchronization effect when acting on a physiologically realistic partially
synchronous dynamics, and provides an example of how to estimate the
stimulation effect.Comment: 19 pages, 8 figure
Social workers in community care practice: Ideologies and interactions with older people
This article is available open access through the publisher’s website through the link below. Copyright @ 2008 The Authors.Since the inception of the NHS and Community Care in 1990, there has been a proliferation of studies examining its implementation at the front line. Considerable attention has been aimed at understanding how it is that social work practitioners, charged with the responsibility to implement community care recommendations for older people, are doing so in a challenging care environment. How a practitioner's ideological frame of reference may impact on his/her practice interactions remains relatively unanswered. However, the course by which professional ideology matures and then directs practice would appear to both complex and multifaceted. The outcome is one that may render the professional both powerful and political, and one that may leave the older care recipient both vulnerable and stigmatized. This paper explores community care practice with older people, emphasizing the ideological underpinnings in practice and their influence on practice interactions. Social work practitioners working on older people's teams in two contrasting communities in England were interviewed to discuss their assessment and care management interactions with older people. Using grounded theory and Goffman's theoretical constructs within frame analysis, a conceptual model for practice emerged, reinforcing that practitioners' understandings of social events, anchored in government and professional discourse and individual perceptions about older people, enabled them to organize and influence the interaction to lead to a professionally determined outcome. The routine work of assessment and care management became very powerful in absence of strategic intention by the practitioner. A move to more strategic behaviour occurred when practice dilemmas required practitioners to intervene, informed by their professionally based values juxtaposed against those supported within official discourse. The findings provide an insight into how social work practitioners manage to deliver community care in a complex environment. The outcomes also reinforce the need for practitioners to develop an understanding of how they construct their social realities, as this may impact on the experience of community care for older people
Contemporary medical television and crisis in the NHS
This article maps the terrain of contemporary UK medical television, paying particular attention to Call the Midwife as its centrepiece, and situating it in contextual relation to the current crisis in the NHS. It provides a historical overview of UK and US medical television, illustrating how medical television today has been shaped by noteworthy antecedents. It argues that crisis rhetoric surrounding healthcare leading up to the passing of the Health and Social Care Act 2012 has been accompanied by a renaissance in medical television. And that issues, strands and clusters have emerged in forms, registers and modes with noticeable regularity, especially around the value of affective labour, the cultural politics of nostalgia and the neoliberalisation of healthcare
Neural Dynamics in Parkinsonian Brain:The Boundary Between Synchronized and Nonsynchronized Dynamics
Synchronous oscillatory dynamics is frequently observed in the human brain.
We analyze the fine temporal structure of phase-locking in a realistic network
model and match it with the experimental data from parkinsonian patients. We
show that the experimentally observed intermittent synchrony can be generated
just by moderately increased coupling strength in the basal ganglia circuits
due to the lack of dopamine. Comparison of the experimental and modeling data
suggest that brain activity in Parkinson's disease resides in the large
boundary region between synchronized and nonsynchronized dynamics. Being on the
edge of synchrony may allow for easy formation of transient neuronal
assemblies
The experiences of patients and carers in the daily management of care at the end of life
Background
Home is the preferred location for most people with an advanced disease and at the end of life. A variety of care professionals work in community settings to provide support to this population. Patients and their spouses, who also care for them (spouse-carers), are rarely accompanied by these sources of support at all times, and have to manage independently between their contact with care professionals.
Aim
To explore how patients and spouse-carers manage their involvement with care professionals in the community setting.
Method
Interpretive phenomenology informs the design of the research, whereby 16 interviews were conducted with the patients and spouse-carers. Interviews were recorded and transcribed verbatim. Data were analysed using phenomenological techniques including template analysis.
Findings
Patients and spouse-carers were interdependent and both parties played a role in co-ordinating care and managing relationships with professional care providers. The patients and spouse-carers actively made choices about how to manage their situation, and develop and modify managing strategies based on their experiences.
Conclusions
When daily management is effective and care professionals acknowledge the dyadic nature of the patient and spouse-carer relationship, people have confidence in living with advanced disease
Two-dimensional vibronic spectroscopy of molecular aggregates: Trimers, dimers, and monomers
The two-dimensional (2D) vibronic spectroscopy of molecular trimers is studied theoretically. The solution of the time-dependent Schrödinger equation is carried out with the multi-configurational time-dependent Hartree (MCTDH) method which allows for an efficient propagation of the multi-component wave functions. 2D-spectra are calculated for H- and J-type aggregates incorporating one or two vibrational modes for each monomer. In performing calculations for monomer, dimer, and trimer systems, it is documented how the vibronic structure of the 2D-spectrum changes upon aggregation. This is of importance for the characterization of aggregation behavior being influenced by experimental conditions such as temperature or concentration
The Physics of the Antarctic Circumpolar Current
A region of transition of surface water characteristics from subantarctic to Antarctic and an associated eastward flowing Antarctic Circumpolar Current (ACC) have long been recognized to exist as a band around Antarctica. In this review we summarize the most important observational and theoretical findings of the past decade regarding the ACC, identify gaps in our knowledge, and recommend studies to address these. The nature of the meridional zonation of the ACC is only now being revealed. The ACC seems to exist as multiple narrow jets imbedded in, or associated with, density fronts (the Subantarctic and Polar fronts) which appear to be circumpolar in extent. These fronts meander, and current rings form from them; lateral frontal shifts of as much as 100km in 10 days have been observed. The volume transport of the ACC has been estimated many times with disparate results
Excitations of attractive 1-D bosons: Binding vs. fermionization
The stationary states of few bosons in a one-dimensional harmonic trap are
investigated throughout the crossover from weak to strongly attractive
interactions. For sufficient attraction, three different classes of states
emerge: (i) N-body bound states, (ii) bound states of smaller fragments, and
(iii) gas-like states that fermionize, that is, map to ideal fermions in the
limit of infinite attraction. The two-body correlations and momentum spectra
characteristic of the three classes are discussed, and the results are
illustrated using the soluble two-particle model.Comment: 7 pages, 5 figure
The Rules of Human T Cell Fate in vivo.
The processes governing lymphocyte fate (division, differentiation, and death), are typically assumed to be independent of cell age. This assumption has been challenged by a series of elegant studies which clearly show that, for murine cells in vitro, lymphocyte fate is age-dependent and that younger cells (i.e., cells which have recently divided) are less likely to divide or die. Here we investigate whether the same rules determine human T cell fate in vivo. We combined data from in vivo stable isotope labeling in healthy humans with stochastic, agent-based mathematical modeling. We show firstly that the choice of model paradigm has a large impact on parameter estimates obtained using stable isotope labeling i.e., different models fitted to the same data can yield very different estimates of T cell lifespan. Secondly, we found no evidence in humans in vivo to support the model in which younger T cells are less likely to divide or die. This age-dependent model never provided the best description of isotope labeling; this was true for naïve and memory, CD4+ and CD8+ T cells. Furthermore, this age-dependent model also failed to predict an independent data set in which the link between division and death was explored using Annexin V and deuterated glucose. In contrast, the age-independent model provided the best description of both naïve and memory T cell dynamics and was also able to predict the independent dataset
- …