The development of the head direction system before eye opening in the rat.

Head direction (HD) cells are neurons found in the hippocampal formation and connected areas that fire as a function of an animal's directional orientation relative to its environment. They integrate self-motion and environmental sensory information to update directional heading. Visual landmarks, in particular, exert strong control over the preferred direction of HD cell firing. The HD signal has previously been shown to appear adult-like as early as postnatal day 16 (P16) in the rat pup, just after eye opening and coinciding with the first spontaneous exploration of its environment. In order to determine whether the HD circuit can begin its organization prior to the onset of patterned vision, we recorded from the anterodorsal thalamic nucleus (ADN) and its postsynaptic target in the hippocampal formation, the dorsal pre-subiculum (PrSd), before and after eye opening in pre-weanling rats. We find that HD cells can be recorded at the earliest age sampled (P12), several days before eye opening. However, this early HD signal displays low directional information content and lacks stability both within and across trials. Following eye opening, the HD system matures rapidly, as more cells exhibit directional firing, and the quality and reliability of the directional signal improves dramatically. Cue-rotation experiments show that a prominent visual landmark is able to control HD responses within 24 hr of eye opening. Together, the results suggest that the directional network can be organized independently of visual spatial information while demonstrating the importance of patterned vision for accurate and reliable orientation in space

Theta-modulated place-by-direction cells in the hippocampal formation in the rat

We report the spatial and temporal properties of a class of cells termed theta-modulated place-by-direction (TPD) cells recorded from the presubicular and parasubicular cortices of the rat. The firing characteristics of TPD cells in open-field enclosures were compared with those of the following two other well characterized cell classes in the hippocampal formation: place and head-direction cells. Unlike place cells, which code only for the animal's location, or head-direction cells, which code only for the animal's directional heading, TPD cells code for both the location and the head direction of the animal. Their firing is also strongly theta modulated, firing primarily at the negative-to-positive phase of the locally recorded theta wave. TPD theta modulation is significantly stronger than that of place cells. In contrast, the firing of head-direction cells is not modulated by theta at all. In repeated exposures to the same environment, the locational and directional signals of TPD cells are stable. When recorded in different environments, TPD locational and directional fields can uncouple, with the locational field shifting unpredictably ("remapping"), whereas the directional preference remains similar across environments

Dzyaloshinsky-Moriya interaction in vesignieite: A route to freezing in a quantum kagome antiferromagnet

We report an electron spin resonance investigation of the geometrically frustrated spin-1/2 kagome antiferromagnet vesignieite, BaCu$_3$V$_2$O$_8$(OH)$_2$. Analysis of the line widths and line shifts indicates the dominance of in-plane Dzyaloshinsky-Moriya anisotropy that is proposed to suppress strongly quantum spin fluctuations and thus to promote long-range ordering rather than a spin-liquid state. We also evidence an enhanced spin-phonon contribution that might originate from a lattice instability and discuss the origin of a low-temperature mismatch between intrinsic and bulk susceptibility in terms of local inhomogeneity

Place Cell Networks in Pre-weanling Rats Show Associative Memory Properties from the Onset of Exploratory Behavior

Place cells are hippocampal pyramidal cells that are active when an animal visits a restricted area of the environment, and collectively their activity constitutes a neural representation of space. Place cell populations in the adult rat hippocampus display fundamental properties consistent with an associative memory network: the ability to 1) generate new and distinct spatial firing patterns when encountering novel spatial contexts or changes in sensory input ("remapping") and 2) reinstate previously stored firing patterns when encountering a familiar context, including on the basis of an incomplete/degraded set of sensory cues ("pattern completion"). To date, it is unknown when these spatial memory responses emerge during brain development. Here, we show that, from the age of first exploration (postnatal day 16) onwards, place cell populations already exhibit these key features: they generate new representations upon exposure to a novel context and can reactivate familiar representations on the basis of an incomplete set of sensory cues. These results demonstrate that, as early as exploratory behaviors emerge, and despite the absence of an adult-like grid cell network, the developing hippocampus processes incoming sensory information as an associative memory network

Examining Healthcare Professionals\u27 Acceptance oF Electronic Medical Records Using UTAUT

With the growing demand for digital information in health care, the electronic medical record (EMR) represents the foundation of health information technology. It is essential, however, in an industry still largely dominated by paper-based records, that such systems be accepted and used. This research evaluates registered nurses’, certified nurse practitioners and physician assistants’ acceptance of EMR’s as a means to predict, define and enhance use. The research utilizes the Unified Theory of Acceptance and Use of Technology (UTAUT) as the theoretical model, along with the Partial Least Square (PLS) analysis to estimate the variance. Overall, the findings indicate that UTAUT is able to provide a reasonable assessment of health care professionals’ acceptance of EMR’s with social influence a significant determinant of intention and use

Spin-orbit effects in Na4_4Ir3_3O8_8, a hyper-kagom\'{e} lattice antiferromagnet

We consider spin-orbit coupling effects in Na$_4$Ir$_3$O$_8$, a material in which Ir$^{4+}$ spins form an hyper-kagom\'{e} lattice, a three-dimensional network of corner-sharing triangles. We argue that both low temperature thermodynamic measurements and the impurity susceptibility induced by dilute substitution of Ti for Ir are suggestive of significant spin-orbit effects. Because of uncertainties in the crystal-field parameters, we consider two limits in which the spin-orbit coupling is either weak or strong compared to the non-cubic atomic splittings. A semi-microscopic calculation of the exchange Hamiltonian confirms that indeed large antisymmetric Dzyaloshinskii-Moriya (DM) and/or symmetric exchange anisotropy may be present. In the strong spin-orbit limit, the Ir-O-Ir superexchange contribution consists of unfrustrated strong symmetric exchange anisotropy, and we suggest that spin-liquid behavior is unlikely. In the weak spin-orbit limit, and for strong spin-orbit and direct Ir-Ir exchange, the Hamiltonian consists of Heisenberg and DM interactions. The DM coupling is parametrized by a three component DM vector (which must be determined empirically). For a range of orientation of this vector, frustration is relieved and an ordered state occurs. For other orientations, even the classical ground states are very complex. We perform spin-wave and exact diagonalization calculations which suggest the persistence of a quantum spin liquid in the latter regime. Applications to Na$_4$Ir$_3$O$_8$ and broader implications are discussed.Comment: 22 pages, 15 figures. submit to prb. New references are adde

Solar Wind and Energy Resource Assessment (SWERA): A Usability Case Study

The Solar Wind and Energy Resource Assessment (SWERA) project focused on providing renewable energy planning resources to the public. Examples include wind, solar, and hydro assessments. A major component of the SWERA website is the archive search. This provides for a discovery DSS upon which users can find and access renewable energy data and supporting models. The RREX component of SWERA provides a visualization DSS as an addition to the website archive. RREX provides the discovery through a couple different avenues. RREX maps the renewable energy data that it provides along with a graphing application of the same data. RREX also provides a web service approach to allow for the distribution of the same data sets in multiple forms. The objective of this paper is to evaluate user satisfaction with the system as well as highlight factors affecting user satisfaction and experience. In the paper we provide a discussion of various design decisions used in the construction of the system followed by description of research methodology, and a discussion of key findings. Overall, analysis of results indicates general acceptance of the functionality provided and highlights venues for further improvements of the interface

Evaluating the impact of electronic health records on clinical reasoning performance

This paper adapts and extends the task-technology fit model of performance to the health care domain and the clinical reasoning task. Central to this effort was careful adaptation of the task and technology characteristics constructs to the clinical reasoning task and electronic health record technology. Overall the results indicate a good fit between model and data. The contributions of this study include successful adaptation of a corner-stone information systems theory to a new domain and technology, a validated user evaluation instrument able to assess the impact of EHR use on clinical reasoning performance, and new insight on the factors that impact task-technology fit and clinical reasoning performance

Beyond Meaningful Use: A Model for Evaluating Electronic Health Record Success

This paper presents a conceptual model for the evaluation of electronic health records. The model is grounded in IS models for evaluating system success and task-technology fit, and integrates concepts of meaningful use and outcome research to arrive at a holistic conceptualization of evaluating the success of EHR. The paper presents numerous issues and challenges to the practice of health care outcomes research, and offers practical solutions for overcoming them