3,341 research outputs found

    PACAP and migraine headache: immunomodulation of neural circuits in autonomic ganglia and brain parenchyma.

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    The discovery that intravenous (IV) infusions of the neuropeptide PACAP-38 (pituitary adenylyl cyclase activating peptide-38) induced delayed migraine-like headaches in a large majority of migraine patients has resulted in considerable excitement in headache research. In addition to suggesting potential therapeutic targets for migraine, the finding provides an opportunity to better understand the pathological events from early events (aura) to the headache itself. Although PACAP-38 and the closely related peptide VIP (vasoactive intestinal peptide) are well-known as vasoactive molecules, the dilation of cranial blood vessels per se is no longer felt to underlie migraine headaches. Thus, more recent research has focused on other possible PACAP-mediated mechanisms, and has raised some important questions. For example, (1) are endogenous sources of PACAP (or VIP) involved in the triggering and/or propagation of migraine headaches?; (2) which receptor subtypes are involved in migraine pathophysiology?; (3) can we identify specific anatomical circuit(s) where PACAP signaling is involved in the features of migraine? The purpose of this review is to discuss the possibility, and supportive evidence, that PACAP acts to induce migraine-like symptoms not only by directly modulating nociceptive neural circuits, but also by indirectly regulating the production of inflammatory mediators. We focus here primarily on postulated extra-dural sites because potential mechanisms of PACAP action in the dura are discussed in detail elsewhere (see X, this edition)

    Extracting Conflict-free Information from Multi-labeled Trees

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    A multi-labeled tree, or MUL-tree, is a phylogenetic tree where two or more leaves share a label, e.g., a species name. A MUL-tree can imply multiple conflicting phylogenetic relationships for the same set of taxa, but can also contain conflict-free information that is of interest and yet is not obvious. We define the information content of a MUL-tree T as the set of all conflict-free quartet topologies implied by T, and define the maximal reduced form of T as the smallest tree that can be obtained from T by pruning leaves and contracting edges while retaining the same information content. We show that any two MUL-trees with the same information content exhibit the same reduced form. This introduces an equivalence relation in MUL-trees with potential applications to comparing MUL-trees. We present an efficient algorithm to reduce a MUL-tree to its maximally reduced form and evaluate its performance on empirical datasets in terms of both quality of the reduced tree and the degree of data reduction achieved.Comment: Submitted in Workshop on Algorithms in Bioinformatics 2012 (http://algo12.fri.uni-lj.si/?file=wabi

    Antiferromagnetism at the YBa2Cu3O7 / La2/3Ca1/3MnO3 interface

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    The magnetic properties of a series of YBa2Cu3O7-x/La2/3Ca1/3MnO3 (YBCO/LC1/3MO) superlattices grown by dc sputtering at high oxygen pressures (3.5 mbar) show the expected ferromagnetic behaviour. However, field cooled hysteresis loops at low temperature show the unexpected existence of exchange bias, effect associated with the existence of ferromagnetic/antiferromagnetic (F/AF) interfaces. The blocking temperature (TB) is found thickness dependent and the exchange bias field (HEB) is found inversely proportional to the FM layer thickness, as expected. The presence of an AF material is probably associated to interface disorder and Mn valence shift towards Mn4+.Comment: 12 pages, 2 figures, 1 table, submitted to Applied Physics Letter

    A quantitative dendritic analysis of four functionally distinct areas of human cerebral cortex

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    Recent investigations have begun to elucidate the function of dendritic arbors, revealing that the geometry of dendrites and the presence of dendritic spines play important roles in both simulated and actual dendritic function (Midtgaard, 1994). The present study attempts to correlate dendritic complexity with cortical function under the assumption that connectivity in a local cortical area may determine its more holistic functional properties. Two human brains (ages: 23 and 69 years) were used for the present study. Four cortical areas (Brodmann\u27s [1908] areas 3, 1, and 2; area 22; area 44; and area 10), respectively representing Benson\u27s four levels of cortical function (primary, unimodal, heteromodal, and supramodal; 1993, 1994), were stained with the modified rapid Golgi technique (Scheibel & Scheibel, 1978). Twenty supragranular pyramidal cells per cortical level were selected (N = 80). Basilar dendritic systems were analyzed using the Neurolucida computer/microscope interface system (Microbrightfield, Inc.). Dendritic measures, which included total dendritic length (TDL), mean dendritic length (MDL), dendritic segment count (DSC), dendritic spine number (DSN), and dendritic spine density (DSD), were used to determine dendritic complexity. All dendritic measures, with the exception of MDL, increased from primary to supramodal cortex. The present findings are consistent with previous research correlating dendritic measures and cortical function (Larsen, Wainwright, Swanson, & Jacobs, 1994; Scheibel, Conrad, Perdue, Tomiyasu, & Wechsler, 1990; Scheibel et al., 1985) and suggest that dendritic extent is related to the functional capabilities of human cerebral cortex

    A KINEMATIC ANALYSIS OF FINGER MOTION IN ARCHERY

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    This paper examines finger motion during the bow string release in archery. METHOD: Fifty-six shots from one athlete were captured with an infrared motion tracking system. Kinematics for index, third and ring fingers were calculated. Two different kinematic variables were defined, related to the proximal interphalangeal joint (PIP) of the third finger: maximum angular velocity (MAX) and minimum angular velocity (MIN). For statistical analysis shots were separated into two groups (very good shots: shots which hit the innermost score area and bad shots: score of 8 or less; shots which achieved a nine or a ten were excluded). A Mann-Whitney test was used. RESULTS: No significant differences were found in the variables MAX and MIN between very good and bad shots (p > 0.05). CONCLUSION: Findings in this study show that there are no significant differences in angular velocity (related to the PIP joint) between very good and bad shots, but that reproducibility of kinematic characteristics are possible crucial factors in archer’s performance

    Strong Enhancement of the Critical Current at the Antiferromagnetic Transition in ErNi2B2C Single Crystals

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    We report on transport and magnetization measurements of the critical current density Jc in ErNi2B2C single crystals that show strongly enhanced vortex pinning at the Neel temperature TN and low applied fields. The height of the observed Jc peak decreases with increasing magnetic field in clear contrast with that of the peak effect found at the upper critical field. We also performed the first angular transport measurements of Jc ever conducted on this compound. They reveal the correlated nature of this pinning enhancement, which we attribute to the formation of antiphase boundaries at TN.Comment: 3 figure

    Patterns in Team Communication during a Simulation Game

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    The development of communication skills is a necessary preparation for effective engineering teamwork. Argyris\u27 Theory of Action provides a framework for understanding patterns in team dialogue. Students can benefit from an awareness of these patterns. The theory highlights the detection and correction of errors by sharing information during group collaboration and interactions. Quality decision-making can be enhanced when members of a team develop high degrees of openness and interdependence. Quality decision-making can be diminished when members of a team regulate the information shared within the team. This work analyzes team interactions from simulation games used in an interdisciplinary engineering course as a team training exercise. Communication patterns of the student teams are selected that model effective and ineffective behaviors. Positive and negative excerpts from actual student interactions are discussed as instructional vehicles for student training on teamwork skills and for guiding student understanding of simulation game dynamics

    Superficial brachioradial artery (radial artery originating from the axillary artery): a case report and embryological background

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    A case of anomalous terminal branching of the axillary artery, concerning the variant called superficial brachioradial artery (arteria brachioradialis superficialis) was described, with special regard to its embryological origin. The left upper limb of a male cadaver was dissected in successive steps from the axillary fossa distally to the palmar region. A variant artery, stemming from the end of the third segment of the axillary artery, followed a superficial course distally. It skipped the cubital fossa, ran on the lateral side of the forearm, crossed ventrally to the palm, and terminated in the deep palmar arch. This vessel is a case of so-called “brachioradial artery” (inexactly called a “radial artery with a high origin”). The origin of the brachioradial artery directly from the axillary artery belongs to the rare variants of the arterial pattern of the upper limb. Its incidence is approximately 3%. Moreover, this vascular variant was associated with another one concerning the brachial plexus. The medial cutaneous nerve of the forearm joined the median nerve in the middle third of the arm and ran further distally as a common trunk, as the normal median nerve does. Anatomical knowledge of the axillary region is crucial for radiodiagnostic and surgical procedures, especially in cases of trauma. The superficially located artery brings an elevated risk of bleeding complications in unexpected situations
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