Phase and amplitude dynamics of nonlinearly coupled oscillators.

This paper addresses the amplitude and phase dynamics of a large system of nonlinearly coupled, non-identical damped harmonic oscillators, which is based on recent research in coupled oscillation in optomechanics. Our goal is to investigate the existence and stability of collective behaviour which occurs due to a play-off between the distribution of individual oscillator frequency and the type of nonlinear coupling. We show that this system exhibits synchronisation, where all oscillators are rotating at the same rate, and that in the synchronised state the system has a regular structure related to the distribution of the frequencies of the individual oscillators. Using a geometric description, we show how changes in the non-linear coupling function can cause pitchfork and saddle-node bifurcations which create or destroy stable and unstable synchronised solutions. We apply these results to show how in-phase and anti-phase solutions are created in a system with a bi-modal distribution of frequencies.

Synchronization in a mechanical resonator array coupled quadratically to a common electromagnetic field mode.

Optomechanical systems are based on the nonlinear coupling between the electromagnetic (EM) field in a resonator and one or more bulk mechanical resonators such that the frequency of the EM field resonator depends on the displacement coordinates of each of the mechanical resonators. In this paper we consider the case of multiple mechanical resonators interacting with a common field for which the frequency of the EM resonance is tuned to depend quadratically (to lowest order) on the displacement of the resonators. By using the method of amplitude equations around a critical point, it is shown that groups of near-identical bulk mechanical resonators with low driving fail to synchronize unless their natural frequencies are identical, in which case the resulting system can exhibit multistability.

Critical fluctuations in cortical models near instability.

Computational studies often proceed from the premise that cortical dynamics operate in a linearly stable domain, where fluctuations dissipate quickly and show only short memory. Studies of human electroencephalography (EEG), however, have shown significant autocorrelation at time lags on the scale of minutes, indicating the need to consider regimes where non-linearities influence the dynamics. Statistical properties such as increased autocorrelation length, increased variance, power law scaling, and bistable switching have been suggested as generic indicators of the approach to bifurcation in non-linear dynamical systems. We study temporal fluctuations in a widely-employed computational model (the Jansen-Rit model) of cortical activity, examining the statistical signatures that accompany bifurcations. Approaching supercritical Hopf bifurcations through tuning of the background excitatory input, we find a dramatic increase in the autocorrelation length that depends sensitively on the direction in phase space of the input fluctuations and hence on which neuronal subpopulation is stochastically perturbed. Similar dependence on the input direction is found in the distribution of fluctuation size and duration, which show power law scaling that extends over four orders of magnitude at the Hopf bifurcation. We conjecture that the alignment in phase space between the input noise vector and the center manifold of the Hopf bifurcation is directly linked to these changes. These results are consistent with the possibility of statistical indicators of linear instability being detectable in real EEG time series. However, even in a simple cortical model, we find that these indicators may not necessarily be visible even when bifurcations are present because their expression can depend sensitively on the neuronal pathway of incoming fluctuations.

Synchronization of many nanomechanical resonators coupled via a common cavity field.

Using amplitude equations, we show that groups of identical nanomechanical resonators, interacting with a common mode of a cavity microwave field, synchronize to form a single mechanical mode which couples to the cavity with a strength dependent on the squared sum of the individual mechanical-microwave couplings. Classically this system is dominated by periodic behavior which, when analyzed using amplitude equations, can be shown to exhibit multistability. In contrast, groups of sufficiently dissimilar nanomechanical oscillators may lose synchronization and oscillate out of phase at significantly higher amplitudes. Further, the method by which synchronization is lost resembles that for large amplitude forcing which is not of the Kuramoto form.

The slow death of psychiatric nursing: what next?

Nursing has always struggled for recognition and status, and there has always been exploitation and shortages, and no more so than in psychiatric settings. Today, however, nursing is in truly dire straits and, as a consequence, psychiatric nursing is more precariously positioned than ever. In order to think constructively about psychiatric nursing's future, it is crucial that this wider context in which it operates is fully appreciated, and this paper begins by summarizing the key features of this context from an international perspective. It is argued that dramatic changes occurring in 'Western' societies call for radical changes in public and professional thinking, and in their vision for health care in the future. Beginning with the general nursing context, this paper depicts the perilous state of psychiatric nursing and mental health care in Australia and elsewhere, and suggests some of the causal factors. It concludes by arguing that the future mental health workforce should be a graduate specialist who stands outside existing disciplinary identities.

Postdisciplinarity in mental health-care: an Australian viewpoint.

This paper outlines some of the powerful forces progressively undermining the conceptual and practical foundations upon which the major disciplines have been established, and dissolving the boundaries which have traditionally distinguished them from each other, particularly those disciplines involved in the healthcare enterprise. It discusses some of the implications of these processes for mental health nursing, and champions a new cadre of 'postdisciplinary' staff, comprising a graduate generic mental healthcare worker and a postgraduate clinical specialist. It is argued that such a specialist --- a 'Generic Mental Health Worker' --- should be welcomed by all those who want to see improved quality of care in mental health services rather than defend a failing system.

Legal and ethical aspects of seclusion: an Australian perspective.

The debate about the appropriateness of seclusion as a nursing practice in inpatient settings in the 21st century continues, with powerful and often emotive arguments from those who view it as an anachronistic and punitive form of ward management, and from others who see it as a useful emergency measure to protect individuals from imminent harm. This is the first paper, however, to focus on legal and ethical issues in relation to the use of seclusion, with policies and practices in Australian psychiatric institutions viewed within the context of worldwide trends. The interplay of ethical principles and international mental health law has encouraged a move towards the provision of care and treatment of the disturbed psychiatric patient within the least restrictive environment, supposedly reducing the potential for the inappropriate use of control mechanisms. Nevertheless, current legislation can be seen to preserve the status quo because it legitimizes seclusion as an acceptable nursing practice, albeit within given parameters, thereby defusing the imperative to promote the reduction and abolition of psychiatric control mechanisms and seek new possibilities in mental health care.

Potential use of lipoxygenase inhibitors for cancer chemoprevention.

Increasing evidence suggests that lipoxygenase (LO)-catalysed metabolites have a profound influence on the development and progression of human cancers. Compared with normal tissues, significantly elevated levels of LO products have been found in breast tumours, colon cancers, lung, skin and prostate cancers, as well as in cells from patients with both acute and chronic leukaemias. LO-mediated products elicit diverse biological activities needed for neoplastic cell growth, influencing growth factor and transcription factor activation, oncogene induction, stimulation of tumour cell adhesion and regulation of apoptotic cell death. Agents that block LO catalytic activity may be effective in preventing cancer by interfering with signalling events needed for tumour growth. In the past ten years, pharmaceuticals agents that specifically inhibit the 5-LO metabolic pathway have been developed to treat inflammatory diseases such as asthma, arthritis and psoriasis. Some of these compounds possess anti-oxidant properties and may be effective in preventing cancer by blocking free radical-induced genetic damage or by preventing the metabolic activation of carcinogens. Other compounds may work by negatively modulating DNA synthesis. Pharmacological profiles of potential chemopreventive agents are compiled from enzyme assays, in vitro testing (e.g., cell proliferation inhibition in human cancer cells) and in vivo animal carcinogenesis models (e.g., N-methyl-N-nitrosourea-induced rat mammary cancer, benzo(a)pyrene-induced lung tumours in strain A/J mice and hormone-induced prostate tumours in rats). In this way, compounds are identified for chemoprevention trials in human subjects. Based on currently available data, it is expected that the prevention of lung and prostate cancer will be initially studied in human trials of LO inhibitors.

Some implications of postmodernism for nursing theory, research, and practice.

This paper explores ways in which some aspects of postmodernist thought impact upon nursing theory and research. The focus is on postmodernist accounts of epistemology and language, in particular notions such as multiple truths, uncertain and provisional knowledge, and claims as to the purposes of knowledge development. Common themes of postmodernism are articulated, including antifoundationalism, the dissonance between competing discourses, and the rejection of "grand theories." The paper concludes with a short set of suggestions for a postmodern approach to nursing practice.

Lipoxygenase inhibitors as potential cancer chemopreventives.

Mounting evidence suggests that lipoxygenase (LO)-catalyzed products have a profound influence on the development and progression of human cancers. Compared with normal tissues, significantly elevated levels of LO metabolites have been found in lung, prostate, breast, colon, and skin cancer cells, as well as in cells from patients with both acute and chronic leukemias. LO-mediated products elicit diverse biological activities needed for neoplastic cell growth, influencing growth factor and transcription factor activation, oncogene induction, stimulation of tumor cell adhesion, and regulation of apoptotic cell death. Agents that block LO-catalyzed activity may be effective in preventing cancer by interfering with signaling events needed for tumor growth. In fact, in a few studies, LO inhibitors have prevented carcinogen-induced lung adenomas and rat mammary gland cancers. During the past 10 years, pharmacological agents that specifically inhibit the LO-mediated signaling pathways are now commercially available to treat inflammatory diseases such as asthma, arthritis, and psoriasis. These well-characterized agents, representing two general drug effect mechanisms, are considered good candidates for clinical chemoprevention studies. One mechanism is inhibition of LO activity (5-LO and associated enzymes, or 12-LO); the second is leukotriene receptor antagonism. Although the receptor antagonists have high potential in treating asthma and other diseases where drug effects are clearly mediated by the leukotriene receptors, enzyme activity inhibitors may be better candidates for chemopreventive intervention, because inhibition of these enzymes directly reduces fatty acid metabolite production, with concomitant damping of the associated inflammatory, proliferative, and metastatic activities that contribute to carcinogenesis. However, because receptor antagonists have aerosol formulations and possible antiproliferative activity, they may also have potential, particularly in the lung, where topical application of such formulations is feasible.

Attitudes toward service use among wife caregivers of frail older veterans.

This study investigated (a) attitudes toward service use among wife caregivers of frail older veterans; and (b) the relationship between those attitudes and service utilization by the wives. The study focused on three sets of attitudinal variables: attitudes towards various kinds of dependencies; individual and family ethos concerning service use; and perceptions of responsibility for care. Respondents were 80 wife caregivers of frail older (age 55+) veterans at a Department of Veterans Affairs Medical Center in a Midwestern state. Most caregivers agreed that it is acceptable to get help with the physical care of the husband and to get help themselves for the emotional strains caused by caregiving. Acceptability of a wife's getting help with the physical care of her husband was a positive predictor of number of services ever used and frequency of in-home service use. Wives' view that help from outside agencies should be used only as a last resort was the strongest and most consistent negative predictor of both number of services ever used and frequency of service use.

Preclinical drug development paradigms for chemopreventives.

Preclinical screening studies and animal efficacy testing models currently are used by the National Cancer Institute's chemoprevention drug discovery program to assess and identify chemical agents and natural products that may have the potential to prevent human cancer. Identification of potential cancer preventing agents begins by subjecting each compound to a sequential series of short-term, in vitro prescreens of mechanistic, biochemical assays to provide quantitative data to help establish an early indication of chemopreventive efficacy and to assist in prioritizing agents for further evaluation in longer-term, in vitro transformation bioassays and whole animal models. Promising chemical agents or combinations of agents that work through different inhibitory mechanisms subsequently are tested in well-established, chemically induced, animal tumor models, which include models of the lung, bladder, mammaries, prostate, and skin. These preclinical bioassays afford a strategic framework for evaluating agents according to defined criteria, and not only provide evidence of agent efficacy, but also serve to generate valuable dose-response, toxicity, and pharmacokinetic data required prior to phase I clinical safety testing. Based on preclinical efficacy and toxicity screening studies, only the most successful agents considered to have potential as human chemopreventives progress into clinical chemoprevention trials.

Culture, needs and nursing: a critical theory approach.

This paper will bring the critique of culture, notably that undertaken by the Frankfurt School of Critical Social Science, to bear on the problem of needs, and expose its significance for the practice and discipline of nursing. The paper begins by reviewing ways in which the idea of 'needs' has been depicted in nursing literature, and it is suggested that this depiction is inadequate in fundamental ways. The critique of existing culture is then outlined and the implications for nursing are suggested in terms of the dissolution of hegemonic practices and the development of a concept of need built around the notion of 'praxis'.

Service utilization by wife caregivers of frail older veterans.

This study investigated patterns and predictors of service utilization among wife caregivers of frail older veterans. The study focused on the following sets of variables: predisposing, enabling, care-receiver need, and caregiver need. Respondents were 80 wife caregivers of frail older (age 55+) veterans at a Department of Veterans Affairs Medical Center (VAMC) in a Midwestern state. Wife caregivers used a mix of VAMC and non-VAMC services. Care-receiver functional status was a significant predictor of both frequency of service use and number of services ever used. Caregivers' perception of service availability and attitude toward service use were the strongest predictors of number of services ever used.

Nazism and nursing: a comment on relevance.

This paper suggest that it is crucial at the present time to look back and consider the role of nurses and the health-care system in the development of Nazi Germany. The paper points out that medical involvement in the Holocaust was extensive and underwritten by the subversion of science to political ends. Evidence is amassed which points to dangerous trends in the conduct of contemporary medicine and to the continuing capacity for institutionally endorsed abuses of human rights. It is suggested that nursing examine its role in the implementation of Nazi policies, so that its continuing susceptibility to political subversion can be recognised, evaluated and neutralised.

The politics of phenomenological concepts in nursing.

This paper challenges those nurses who champion Heideggerian phenomenology, by outlining some of the possible political consequences of that philosophy. Some relationships between phenomenology and fascism are discussed, with special reference to anti-humanism and authenticity. Heidegger's commitment to Nazism is affirmed and, following the lead of other recent contributions to the debate, it is suggested that this was the likely, if not inevitable, result of his phenomenological philosophy. It is concluded that, because of its immanent fascism, Heideggerian phenomenology is at odds with the general value orientation publicly espoused by the nursing profession, and that this may render it not only unsuitable as a means of understanding and elaborating nursing knowledge, but also actively counter-productive to the conventional aspirations of nurses.