Effect of hole-shape irregularities on photonic crystal waveguides

The effect of irregular hole shape on the spectrum and radiation losses of a photonic crystal waveguide is studied using Bloch-mode expansion. Deviations from a perfectly circular hole are characterized by a radius fluctuation amplitude and correlation angle. It is found that the parameter which determines the magnitude of the effect of disorder is the standard deviation of the hole areas. Hence, for a fixed amplitude of the radius fluctuation around the hole, those effects are strongly dependent on the correlation angle of the irregular shape. This result suggests routes to potentially improve the quality of photonic crystal structures.Comment: 3 pages, 3 figure

Being strategic: Utilising consumer views to better promote an expanded role for nurses in Australian general practice

Australian consumers have articulated their perceptions of the role of the nurse in general practice. Practice Nurses (PNs) and General Practitioners (GPs) have also highlighted the issues they believe currently and potentially impact on this role in Australia. This paper identifies and discusses the nexus between the consumers' perceptions and expectations and health professionals' issues. Data collected from focus groups and interviews in 2 Australian studies of consumer perception of nursing in general practice, are re-considered alongside findings reported in the Royal Australian College of General Practitioners and the Royal College of Nursing, Australia report; General Practice Nursing in Australia. Consumers, doctors and nurses working in general practices in Australia, raised similar issues. However, consumers considered these issues in relation to their health care needs, whereas the GPs and PNs tended to focus more on professional and structural tensions related to the current and potentially expanded role of the PN. Understanding consumer views vis-a-vis issues raised by PNs and GPs about the role of nursing in general practice provides direction for both professions to better work with consumers to enhance their understanding of what general practice services could be and how changes, like expanding the role of nurses, may bring about improvements in the health outcomes of consumers. Health professionals can benefit from reflecting on the experiences and expectations of consumers if they desire to make general practice services more responsive to individual consumer's needs and at the same time adopt a primary health care focus

Generation of Neuronal Diversity: Analogies and Homologies with Hematopoiesis

The immense variety of neuronal phenotypes in the vertebrate nervous system is apparent in considering just the process of chemical transmission. There are approximately 12 known classical neurotransmitters and more than 30 neuropeptides thus far identified, and individual neurons simultaneously synthesize, store, and secrete one or more classical transmitters in addition to three or more neuropeptides. The transmitters and peptides are expressed in an exceedingly large number of different combinations in different parts of the nervous system. Although there are useful generalizations as to the frequency of certain transmitter-peptide combinations, there are innumerable exceptions to these rules. How the particular combinations produced in each neuron are specified during development is a challenging question. The magnitude of this problem becomes clear if one calculates the number of possible combinations if a neuron is to produce 2 transmitters out of a possible 12 and 3 peptides out of a possible 30. There are 267,960 different potential phenotypes in this example

Human Time-Frequency Acuity Beats the Fourier Uncertainty Principle

The time-frequency uncertainty principle states that the product of the temporal and frequency extents of a signal cannot be smaller than $1/(4\pi)$. We study human ability to simultaneously judge the frequency and the timing of a sound. Our subjects often exceeded the uncertainty limit, sometimes by more than tenfold, mostly through remarkable timing acuity. Our results establish a lower bound for the nonlinearity and complexity of the algorithms employed by our brains in parsing transient sounds, rule out simple "linear filter" models of early auditory processing, and highlight timing acuity as a central feature in auditory object processing.Comment: 4 pages, 2 figures; Accepted at PR

Evolutionary-thinking in agricultural weed management

Agricultural weeds evolve in response to crop cultivation. Nevertheless, the central importance of evolutionary ecology for understanding weed invasion, persistence and management in agroecosystems is not widely acknowledged. This paper calls for more evolutionarily-enlightened weed management, in which management principles are informed by evolutionary biology to prevent or minimize weed adaptation and spread. As a first step, a greater knowledge of the extent, structure and significance of genetic variation within and between weed populations is required to fully assess the potential for weed adaptation. The evolution of resistance to herbicides is a classic example of weed adaptation. Even here, most research focuses on describing the physiological and molecular basis of resistance, rather than conducting studies to better understand the evolutionary dynamics of selection for resistance. We suggest approaches to increase the application of evolutionary-thinking to herbicide resistance research. Weed population dynamics models are increasingly important tools in weed management, yet these models often ignore intrapopulation and interpopulation variability, neglecting the potential for weed adaptation in response to management. Future agricultural weed management can benefit from greater integration of ecological and evolutionary principles to predict the long-term responses of weed populations to changing weed management, agricultural environments and global climate

Tabula Rasa and Human Nature

It is widely believed that the philosophical concept of 'tabula rasa' originates with Locke's Essay Concerning Human Understanding and refers to a state in which a child is as formless as a blank slate. Given that both these beliefs are entirely false, this article will examine why they have endured from the eighteenth century to the present. Attending to the history of philosophy, psychology, psychiatry and feminist scholarship it will be shown how the image of the tabula rasa has been used to signify an originary state of formlessness, against which discourses on the true nature of the human being can differentiate their position. The tabula rasa has operated less as a substantive position than as a whipping post. However, it will be noted that innovations in psychological theory over the past decade have begun to undermine such narratives by rendering unintelligible the idea of an 'originary' state of human nature

Novel insights into host-fungal pathogen interactions derived from live-cell imaging

Acknowledgments The authors acknowledge funding from the Wellcome Trust (080088, 086827, 075470 and 099215) including a Wellcome Trust Strategic Award for Medical Mycology and Fungal Immunology 097377 and FP7-2007–2013 grant agreement HEALTH-F2-2010-260338–ALLFUN to NARG.Peer reviewedPublisher PD

Complex patterns of local adaptation in teosinte

Populations of widely distributed species often encounter and adapt to specific environmental conditions. However, comprehensive characterization of the genetic basis of adaptation is demanding, requiring genome-wide genotype data, multiple sampled populations, and a good understanding of population structure. We have used environmental and high-density genotype data to describe the genetic basis of local adaptation in 21 populations of teosinte, the wild ancestor of maize. We found that altitude, dispersal events and admixture among subspecies formed a complex hierarchical genetic structure within teosinte. Patterns of linkage disequilibrium revealed four mega-base scale inversions that segregated among populations and had altitudinal clines. Based on patterns of differentiation and correlation with environmental variation, inversions and nongenic regions play an important role in local adaptation of teosinte. Further, we note that strongly differentiated individual populations can bias the identification of adaptive loci. The role of inversions in local adaptation has been predicted by theory and requires attention as genome-wide data become available for additional plant species. These results also suggest a potentially important role for noncoding variation, especially in large plant genomes in which the gene space represents a fraction of the entire genome