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Frequency structure of the nonlinear instability of a dragged viscous thread  [PDF]
Robert L. Welch,Billy Szeto,Stephen W. Morris
Physics , 2012, DOI: 10.1103/PhysRevE.85.066209
Abstract: A thread of viscous fluid falling onto a moving surface exhibits a spectacular variety of types of motion as the surface speed and nozzle height are varied. For modest nozzle heights, four clear regimes are observed. For large surface speed, the thread is dragged into a stretched centenary configuration which is confined to a plane. As the surface speed is lowered, this exhibits a supercritical bifurcation to a meandering state. At very low surface speeds, the state resembles the usual coiling motion of a viscous thread falling on a stationary surface. In between the meandering and coiling regimes, a window containing a novel multifrequency state, previously called "figures of eight" is found. Using an improved visualization technique and a fully automated apparatus, we made detailed measurements of the longitudinal and transverse motion of the thread in all these states. We found that the multifrequency state is characterized by a complex pattern of motion whose main frequencies are locked in a 3:2 ratio. This state appears and disappears with finite amplitude at sharp bifurcations without measurable hysteresis.
Dragged Metrics  [PDF]
M. Novello,E. Bittencourt
Physics , 2012, DOI: 10.1007/s10714-013-1507-z
Abstract: We show that the path of any accelerated body in an arbitrary space-time geometry $g_{\mu\nu}$ can be described as geodesics in a dragged metric $\hat{q}_{\mu\nu}$ that depends only on the background metric and on the motion of the body. Such procedure allows the interpretation of all kind of non-gravitational forces as modifications of the metric of space-time. This method of effective elimination of the forces by a change of the metric of the substratum can be understood as a generalization of the d'Alembert principle applied to all relativistic processes.
Elongated Membrane Tethers, Individually Anchored by High Affinity α4β1/VCAM-1 Complexes, Are the Quantal Units of Monocyte Arrests  [PDF]
Calvin Chu, Emrah Celik, Felix Rico, Vincent T. Moy
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064187
Abstract: The α4β1 integrin facilitates both monocyte rolling and adhesion to the vascular endothelium and is physiologically activated by monocyte chemoattractant protein (MCP-1). The current study investigated the initial events in the adhesion of THP-1 cells to immobilized Vascular Cell Adhesion Molecule 1 (VCAM-1). Using AFM force measurements, cell adhesion was shown to be mediated by two populations of α4β1/VCAM-1 complexes. A low affinity form of α4β1 was anchored to the elastic elements of the cytoskeleton, while a higher affinity conformer was coupled to the viscous elements of the cell membrane. Within 100 ms of contact, THP-1 cells, stimulated by co-immobilized MCP-1, exhibited a tremendous increase in adhesion to VCAM-1. Enhanced cell adhesion was accompanied by a local decoupling of the cell membrane from the cytoskeleton and the formation of long membrane tethers. The tethers were individually anchored by multiple α4β1/VCAM-1 complexes that prolonged the extension of the viscous tethers. In vivo, the formation of these membrane tethers may provide the quantal structural units for the arrest of rolling monocytes within the blood vessels.
Stationary and Transient Work-Fluctuation Theorems for a Dragged Brownian Particle  [PDF]
R. van Zon,E. G. D. Cohen
Physics , 2002, DOI: 10.1103/PhysRevE.67.046102
Abstract: Recently Wang et al. carried out a laboratory experiment, where a Brownian particle was dragged through a fluid by a harmonic force with constant velocity of its center. This experiment confirmed a theoretically predicted work related integrated (I) Transient Fluctuation Theorem (ITFT), which gives an expression for the ratio for the probability to find positive or negative values for the fluctuations of the total work done on the system in a given time in a transient state. The corresponding integrated stationary state fluctuation theorem (ISSFT) was not observed. Using an overdamped Langevin equation and an arbitrary motion for the center of the harmonic force, all quantities of interest for these theorems and the corresponding non-integrated ones (TFT and SSFT, resp.) are theoretically explicitly obtained in this paper. While the (I)TFT is satisfied for all times, the (I)SSFT only holds asymptotically in time. Suggestions for further experiments with arbitrary velocity of the harmonic force and in which also the ISSFT could be observed, are given. In addition, a non-trivial long-time relation between the ITFT and the ISSFT was discovered, which could be observed experimentally, especially in the case of a resonant circular motion of the center of the harmonic force.
An estimation of the mass dragged by the solar wind from Mars’s atmosphere in its geologic history
Héctor Javier Durand-Manterola
Geofísica internacional , 2001,
Abstract: In the past Mars had a denser atmosphere, but it lacks a magnetic field to protect the ionosphere and exosphere from the solar wind. A model for describing the loss of atmosphere in geologic time is presented. The amount of volatiles degassed from Mars was in the order of 193.7 Terrestrial Atmospheric Masses (TAM). The amount of volatiles dragged by the solar wind, if the large chronology is correct, is in the range of 0.472 to 1.89 TAM. If the short chronology is correct, the loss remains in the range of 0.0624 to 0.25 TAM. The amount of volatiles dragged by the solar wind is far less than the degassed mass; hence the drag exerted by the solar wind does not account for the bulk of volatiles lost by Mars.
On Decoupling of Functions of Normal Vectors II  [PDF]
Pavel G. Grigoriev,Stanislav A. Molchanov
Mathematics , 2014,
Abstract: A decoupling type inequality for a sum of functions of Guassian vectors is established.
Nonlinear Decoupling in Process Control
Jens G. Balchen
Modeling, Identification and Control , 1991, DOI: 10.4173/mic.1991.2.3
Abstract: The principle of nonlinear decoupling as a general approach to the control of nonlinear processes is reviewed. A novel technique is introduced for resolving the inverse problem in case the nonlinear process function does not have a closed-form inverse. The paper also indicates the relationships between nonlinear decoupling, 'cascade control' and 'sliding mode control'.
Of chronic diazepam treatments on behavior on individually housed rats
Spasojevi? Nata?a,Gavrilovi? Ljubica,Varagi? V.V.,Dronjak Sla?ana
Archives of Biological Sciences , 2007, DOI: 10.2298/abs0702113s
Abstract: The present study analyzed the effects of chronic treatment with low doses of diazepam on body weight, defecations and urinations, vertical rears, the elevated platform test, and self-grooming in male rats exposed for 21 days to social isolation. The rats were treated for 21 days with diazepam (0.2 mg/kg, i.p) or its vehicle. Social isolation led to decreased body weight and vertical rears, more defecations and urinations, increased reluctance to step down from the test platform, shorter duration of grooming, and longer reluctance to start grooming. Chronic diazepam in individually housed rats produced increase in body weight and vertical rears, decrease in the number of defecations and urinations, and shortening of the time of reluctance to step down from the platform. The number of grooming bouts, their duration, and reluctance to start grooming were not altered by diazepam, but it decreased the percentage of incorrect transitions. The obtained data indicate that chronic diazepam treatment of socially isolated rats changes non-grooming behavior and some grooming behavior parameters. .
Prevalence and Incidence of Abnormal Behaviours in Individually Housed Sheep  [PDF]
Mariko Lauber,Judy A. Nash,Allan Gatt,Paul H. Hemsworth
Animals , 2012, DOI: 10.3390/ani2010027
Abstract: This study examined the prevalence and incidence of abnormal behaviour in sheep housed individually indoors. Ninety-six castrated Merino sheep were observed using 15-min instantaneous sampling between 08:15 and 18:15 h for two consecutive days over a 3-week period. Sheep on average spent 62% of their time idle, 17% feeding, 1% drinking, 5% pacing, 10% chewing pen fixtures and 4% nosing pen fixtures. Pacing behaviour was predominantly seen in the morning with sheep on average spending 14% of their time pacing. Sheep on average spent 4% of their time in the morning and 13% of their time in the afternoon chewing pen fixtures. In the afternoon, the predominant behaviour was idle with sheep on average spending 71% of their time idle. Seventy-one percent of the sheep displayed one or more of the behaviours of pacing, and chewing and nosing pen fixtures for more than 10% of the day and 47% displayed one or more of these behaviours for more than 20% of the day. The prevalence and incidence of these ‘abnormal’ behaviours appears high, especially in relation to that of sheep grazed outdoors on pasture, and raises the question of the welfare risk to these animals. However, without a more comprehensive appreciation of other aspects of the animal’s biology, such as stress physiology and fitness characteristics, it is difficult to understand the welfare implications of these behaviours.
On Decoupling of Massless Modes in NCOS Theories  [PDF]
Seungjoon Hyun,Sangmin Lee,Hyeonjoon Shin
Physics , 2002, DOI: 10.1140/epjc/s2002-01047-8
Abstract: We revisit the decoupling phenomenon of massless modes in the noncommutative open string (NCOS) theories. We check the decoupling by explicit computation in (2+1) or higher dimensional NCOS theories and recapitulate the validity of the decoupling to all orders in perturbation theory.
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