Composite Fermions, Edge Currents and the Fractional Quantum Hall Effect

We present a theory of composite fermion edge states and their transport properties in the fractional and integer quantum Hall regimes. We show that the effective electro-chemical potentials of composite fermions at the edges of a Hall bar differ, in general, from those of electrons. An expression for the difference is given. Composite fermion edge states of three different types are identified. Two of the three types have no analog in previous theories of the integer or fractional quantum Hall effect. The third type includes the usual integer edge states. The direction of propagation of the edge states agrees with experiment. The present theory yields the observed quantized Hall conductances at Landau level filling fractions p/(mp+-1), for m=0,2,4, p= 1,2,3,... It explains the results of experiments that involve conduction across smooth potential barriers and through adiabatic constrictions, and of experiments that involve selective population and detection of fractional edge channels. The relationship between the present work and Hartree theories of composite fermion edge structure is discussed.Comment: 19 pages + 6 figures. Self-unpacking uuencoded postscript. To appear in Physical Review B. Revised version has more details in the Appendix and a discussion of one more experiment in Section

The "Peer" in "Peer Review"

Gad Perry1, Jaime Bertoluci2, Bruce Bury3, Robert W. Hansen4, Robert Jehle5, John Measey6, Brad R. Moon7, Erin Muths8, and Marco A. L. Zuffi9,* 1 Texas Tech University, Lubbock, TX, USA; Journal of Herpetology. 2 Universidade de Sao Paulo, Brazil; Phyllomedusa. 3 USGS, Corvallis, OR, USA; Herpetological Conservation and Biology. 4 Clovis, CA, USA; Herpetological Review. 5 University of Salford, Greater Manchester, UK; Herpetological Journal. 6 University of the Western Cape, South Africa; African Journal of Herpetology. 7 University of Louisiana at Lafayette, LA, USA; Herpetologica. 8 USGS, Fort Collins, CO, USA; Journal of Herpetology. 9 Museum Natural History, University of Pisa, Italy; Acta Herpetologica

The IMPROVE guidelines (Ischaemia Models: Procedural Refinements Of in Vivo Experiments)

Most in vivo models of ischaemic stroke target the middle cerebral artery and a spectrum of stroke severities, from mild to substantial, can be achieved. This review describes opportunities to improve the in vivo modelling of ischaemic stroke and animal welfare. It provides a number of recommendations to minimise the level of severity in the most common rodent models of middle cerebral artery occlusion, while sustaining or improving the scientific outcomes. The recommendations cover basic requirements pre-surgery, selecting the most appropriate anaesthetic and analgesic regimen, as well as intraoperative and post-operative care. The aim is to provide support for researchers and animal care staff to refine their procedures and practices, and implement small incremental changes to improve the welfare of the animals used and to answer the scientific question under investigation. All recommendations are recapitulated in a summary poster (see supplementary information)

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Structural and functional integration of the snake axial system.

Snake locomotor, constriction, and swallowing movements all involve axial bending and twisting movements, but each differs in pattern of movement, speed, duration, and force exertion. All of these movements are produced by the complex axial musculature, of which the epaxial muscles are the longest, mostly complexly interconnected, and largest in cross-sectional areas. Therefore, the epaxial muscles are hypothesized to be important lateral flexors in snakes. I studied the anatomy, kinematics and epaxial muscle activity during lateral undulation, constriction of prey, and post-cranial undulatory swallowing in gopher snakes (Pituophis melanoleucus) and king snakes (Lampropeltis getula). I studied the three behaviors consecutively in each snake, which controlled for differences in electrode placement that could confound results obtained from separate studies on different individuals. The epaxial muscles are active, and serve as important axial flexors, in all three behaviors. During lateral undulation, these muscles produce and propagate axial bends along the trunk. They are active contralateral to points of force exertion and produce long-radius vertebral bends around these points. This propulsive mechanism may be modeled as a type of cam-follower system, in which continuous rotation of the body around sites of force exertion produces forward translation of the snake. Constriction postures, muscular activity patterns, and force exertion are highly variable. The epaxial muscles are active consistently during coil formation and tightening, but discontinuously throughout sustained constriction postures, usually in response to movements of the prey. The epaxial muscles contribute to short-radius vertebral bending during constriction, and therefore do not mechanically conflict with constriction. During swallowing, the epaxial muscles produce and propagate vertebral bends of intermediate-radius, which push ingested prey along the esophagus toward the stomach. These axial bends are kinematically similar to those of lateral undulation and involve similar patterns of epaxial muscle activity. Therefore, despite different directions of force exertion during locomotion and swallowing, the mechanics of vertebral bending are similar in both behaviors. The muscular control and mechanics of axial bending in these three behaviors illustrate some of the ways that the axial musculature is used to overcome the mechanical constraints imposed by the simplified external body form of snakes.Ph.D.Animal PhysiologyBiological SciencesMorphologyZoologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/131491/2/9909949.pd

The mechanics and muscular control of constriction in gopher snakes ( Pituophis melanoleucus ) and a king snake ( Lampropeltis getula )

Constriction of prey by gopher snakes Pituophis melanoleucus and king snakes Lampropeltis getula is highly variable in posture, muscular activity and force exertion. These snakes typically use lateral bends of the anterior trunk to wind the body into a vertical coil around the prey. Three common constriction postures are fully encircling loops that form a coil, partially encircling loops, and non-encircling loops that pinion the prey. Initial tightening of a coil occurs by winding or pressing the loops tighter to reduce the diameter of the coil. The epaxial muscles are highly active during striking and coil formation and intermittently active during sustained constriction. These results refute the hypothesis of a mechanical constraint on constriction in snakes with elongate epaxial muscles. Constricting gopher and king snakes can detect muscular, ventilatory and circulatory movements in rodent prey. In response to simulated heartbeats or ventilation in mice, the snakes twitch visibly, recruit epaxial muscle activity, and increase constriction pressure temporarily, but then quickly relax. Muscular activity and constriction pressure are increased most and sustained longest in response to muscular struggling in prey. Although muscle activity and pressure exertion are intermittent, the constriction posture is maintained until the prey has been completely still for several seconds; thus, a snake can reapply pressure in response to any circulatory, ventilatory or muscular movement by the prey. The pressures of 6.1–30.9 kPa (46–232 mm Hg) exerted on small mammal prey by constricting snakes range from about half to over twice a mouse's systolic blood pressure, and are probably 10 times larger than the venous pressure. These high pressures probably kill mammalian prey by inducing immediate circulatory and cardiac arrest, rather than by suffocation alone.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74530/1/j.1469-7998.2000.tb00823.x.pd