Short Jumps Research Articles

Modeling and Simulating the Dynamics of Type IV Pili Extension of Pseudomonas aeruginosa

Bacteria such as Pseudomonas aeruginosa use type IV pili to move across surfaces. The pili extend, attach to the surface, and then retract to move the bacteria forward. In this article, a coarse-grained model of pilus extension and attachment is developed. Simulations performed at biologically relevant conditions indicate that pilus extension is a quasistatic process such that the pili are able to relax via thermal fluctuations as it is being built and extended. Results are generated for pili with different rigidities ranging from very flexible to very stiff. It is shown that very flexible pili do not extend very far and thus would limit the bacteria to short jumps forward while stiff pili enable much greater displacements. Feasible mechanisms of attachment to the surface are also found to vary greatly between flexible and stiff pili. While it is not always the tip of flexible pili that first makes contact with the substrate, it is likely to be a part of the pili that is close to the tip. Conversely, stiff pili are much more likely to make contact with the substrate via the tip, but if not then the part of the pilus that attaches can be quite far from the tip. These results thus give insight to help resolve current discrepancies in the literature regarding pilus stiffness and the location of adhesins on pili.

Stabilization of alternative current voltage

Two ways to construct a pulse ac voltage stabilizer (PACVS) are discussed in the present paper. In the first one, the acting, average, and amplitude voltages are controlled. An observation interval equal to or a multiple of half of the period of measured voltage is required for it. In the second variant, the instant values of the ac voltages are controlled, which allows one to correct the voltage from and compensate for the short voltage jumps and drops. It is shown that PACVS construction using a booster circuit decreases the demands made on the voltage of transistors and filter capacitor, in addition to impairing the quality of the stabilization and correction of the voltage form. Since it uses the feedback principle of the output voltage form, it is appropriate to construct the PACVS by means of the control principle over disturbance. This enables one to increase the stabilizer speed, since it responds directly to the source of the change in the output voltage rather than the consequence. It is shown that the smoothing action depends on the capacitor capacity and throttle inductance product, while the output resistance and the filter oscillation decrease with increasing capacity and decreasing inductance. An example of a PACVS controlling the instant values of the output voltage and the results of its investigation in MATLAB and Simulink are given.

Latent Jump Diffusion Factor Estimation for Commodity Futures

We introduce a new methodology to estimate the latent factors of a multivariate jump diffusion process illustrated with an application to the commodity futures term structure. Specifically, we propose a new state space form and then use a modified Kalman filter to estimate models with latent jump-diffusion factors. The method is applied to oil and copper futures prices to pin down long and short term jumps in their futures term structure. Estimates of jump arrival times indicate that both important information surprises and market activities generate jumps of different intensities.

Diffusion of Benzene in the Breathing Metal–Organic Framework MIL-53(Cr): A Joint Experimental–Computational Investigation

A combination of experimental (quasi-elastic neutron scattering and 2H NMR) and computational (molecular dynamics) tools was used to uncover the molecular mobility of benzene trapped inside the flexible channel-type MIL-53 (Cr3+) MOF. This material was shown to undergo a contraction of the structure upon benzene adsorption with the formation of a narrow pore phase with a smaller aperture. This confinement was found to strongly influence the dynamics of the guest: benzene diffuses in a region centered in the middle of the pore by a 1D-jump translational mechanism along the tunnel ruled by the presence of the μ2-OH groups present at the MOF pore wall. This translational diffusion is combined with a fast uniaxial rotational motion around the C6-axis. Any other rotational motion that involves the tumbling of the phenyl rings about the channel axis is much less probable due to a high activation energy barrier (49 kJ mol–1). In this way benzene can be pictured as a rotating disc that diffuses rapidly through the central part of the channel by short jumps between neighboring low energy basins located in the vicinity of the μ2-OH groups of the MIL-53 channels.

Fair compensation for gate and wind conditions in ski jumping – estimated from competition data using a mixed model

AbstractSki jumping is a Winter Olympic sport where the athletes try to fly as far as possible with the best possible style on a ski jumping hill. The best athletes may achieve distances around 100 m on the smallest hills and up to 251.5 m (the world record) on a flying hill. The length of a ski jump is affected by the gate from which the jumpers start, where higher gates give higher speed and therefore longer jumps. Wind conditions are also important, head winds tend to give longer jumps and tail winds tend to give shorter jumps. To ensure relatively fair conditions during competitions, a system including gate and wind compensations was introduced from January 2010. If the conditions change considerably during a round, the jury can change the gate number to avoid too long or too short jumps, and the athlete is then given a compensation (positive or negative). Furthermore, the athletes are given a compensation for the wind conditions during their jump. In this paper, the fairness of this compensation system is investigated by an analysis of the results from 80 ski jumping competitions for men arranged in the World Cup, World Championships and Olympics in the 2011/2012, 2012/2013 and 2013/2014 seasons. The analysis is based on a mixed model. I found that the present compensation for gate number is reasonably fair, but with a tendency for 10% over-compensation. On the other hand, I estimate that the present compensation factor for head winds should be increased by 48% (95% CI 40–57%) and for tail winds by 22% (95% CI 16–30%) to fully compensate for wind conditions.

Psychological Bases of a Method of Training to Reading in Primary School

This article research of reading by means of which children receive the information most part, plays a huge role in the course of mastering of knowledge. Its value all increases in conditions of the existing education system assuming development of differentiation and an individualization of training and increase of relative density of self-education of schoolchildren. In these circumstances especially important ability correctly to use reading as means of reception of new knowledge. Confident possession of skills of reading is one of the basic conditions of success of children in the doctrine. However reader's skills of today's schoolchildren cause serious alarm in teachers and at parents. Keywords: reading, mastering skill, sound alphabetical, letters, syllables, words, visual, speech the impellent, speech the acoustical analyzers Reading by means of which children receive the information most part, plays a huge role in the course of mastering of knowledge. Its value all increases in conditions of the existing education system assuming development of differentiation and individualization of training and increase of relative density of self- education of schoolchildren. In these circumstances especially important ability correctly to use reading as means of reception of new knowledge. Confident possession of skills of reading is one of the basic conditions of success of children in the doctrine. However reader's skills of today's schoolchildren cause serious alarm in teachers and at parents. Reading - difficult physiological process. In its certificate take part visual, speech the impellent, speech the acoustical analyzers. At the heart of its process, the most complicated mechanisms of interaction of analyzers and time communications of two alarm systems (Levina, 2000; Zaytsev, 2001). The first operation of reading is the visual perception of graphically presented information (letters, syllables, words). At training to reading the child first of all gets acquainted with visions of letters. Storing of all letters of the alphabet and ability to learn to (identify) each of them is an indispensable condition of mastering by skill of reading. During reading of an eye reading moves along a line short and fast jumps. Between jumps there are pauses, or motionless fixings of objects. The beginning reader does such 10-12 fixings at line, skilled usually enough 3-4 fixings. In the beginning of reading of an eye fix any information (a letter, a syllable) and remain motionless during some time. At this particular time the image is perceived. Further there is a jump, (moving eyes to the right along a line before fixing of the following image, and so till the end of a line. During reading of an eye by means of jumps and fixings reach the end of a line and then make fast regressive jump to the left, to the beginning of the next line, and all repeats at first. Regressive movements of eyes (returning a look from right to left) are necessary on only at transition to the next line, but also for return to already read to specify, checkup understanding of sense, to rectify the committed errors. Frequency of regresses in movements of eyes depends on level of automation of skill of reading: the reader is more skilled, the less than visual regresses it in the course of reading, and, on the contrary, the makes less reader's experience, the more often return to already read. Besides, the quantity of regressive movements of eyes depends on characteristics of the readable text - complexities, novelty, and the importance for reading (Rusetskaya, 2007). Besides regressive movements, at reading are marked and movements of eyes which allow to run

The role of fore- and hindlimbs during jumping in the Dybowski's frog (Rana dybowskii).

Anurans are well known for their jumping abilities, making use of their strong hindlimbs. In contrast, the function of the forelimbs during take-off has rarely been studied. We measured the ground reaction forces exerted by forelimbs and hindlimbs during short jumps in the Dybowski's frog Rana dybowskii. Take-off occurred in two phases. Phase one (from the initial time until the forelimbs took off), which lasts a relatively long time (63.2 ± 4.1% of the total take-off phase, N = 20), provides sufficient time for the forelimbs to elevate the body to a suitable posture to deliver the best take-off angle. Phase two (from the forelimbs lift-off until hindlimbs lift-off) was dominated by the hindlimbs which provided a constant and fast elevation. The force angle (angle of the resultant vector from fore-aft and normal force components towards the plane of the substrate) of the hindlimbs and body trajectory was variable before the forelimbs lifted off of the substrate and then primarily followed the direction of the line from the foot-substrate point to the center of mass (COM). The preparation angle adopted when the forelimbs lifted off of the substrate was a good predictor of the take-off angle. The total normal force oscillated around body weight (BW) before the forelimb normal force peaked. The BW shifted from the hindlimbs to the forelimbs during the initial phase of take-off. A simple lever model suggests that the forelimbs are responsible for raising the COM, thus influencing the take-off angle in short jumps.

Foreign exchange option pricing in the currency cycle with jump risks

This paper examines regime switching behavior and the nature of jumps in foreign exchange rates, as well as their implications in currency option pricing. Considering the characteristics of long swing as well as the short term jumps in exchange rates, we adopt the regime-switching model with jump risks to capture the movement of exchange rates in the developed and emerging countries. Our results show that ‘high-variance’ and ‘low-variance’ describes most of our sample currencies’ trajectories. The regime-switching model with jump risks is proven to capture better exchange rate changes than the regime-switching model (RSM) and the Black–Scholes model (BSM). In addition, our results show that the currency option pricing model when considering regimes of high-variance or low-variance states as well as the jump nature of exchange rates, is better than the traditional BSM and RSM.

Insights into Cell Membrane Microdomain Organization from Live Cell Single Particle Tracking of the IgE High Affinity Receptor FcϵRI of Mast Cells

Current models propose that the plasma membrane of animal cells is composed of heterogeneous and dynamic microdomains known variously as cytoskeletal corrals, lipid rafts and protein islands. Much of the experimental evidence for these membrane compartments is indirect. Recently, live cell single particle tracking studies using quantum dot-labeled IgE bound to its high affinity receptor FcϵRI, provided direct evidence for the confinement of receptors within micrometer-scale cytoskeletal corrals. In this study, we show that an innovative time-series analysis of single particle tracking data for the high affinity IgE receptor, FcϵRI, on mast cells provides substantial quantitative information about the submicrometer organization of the membrane. The analysis focuses on the probability distribution function of the lengths of the jumps in the positions of the quantum dots labeling individual IgE FcϵRI complexes between frames in movies of their motion. Our results demonstrate the presence, within the micrometer-scale cytoskeletal corrals, of smaller subdomains that provide an additional level of receptor confinement. There is no characteristic size for these subdomains; their size varies smoothly from a few tens of nanometers to a over a hundred nanometers. In QD-IGE labeled unstimulated cells, jumps of less than 70 nm predominate over longer jumps. Addition of multivalent antigen to crosslink the QD-IgE-FcϵRI complexes causes a rapid slowing of receptor motion followed by a long tail of mostly jumps less than 70 nm. The reduced receptor mobility likely reflects both the membrane heterogeneity revealed by the confined motion of the monomeric receptor complexes and the antigen-induced cross linking of these complexes into dimers and higher oligomers. In both cases, the probability distribution of the jump lengths is well fit, from 10 nm to over 100 nm, by a novel power law. The fit for short jumps suggests that the motion of the quantum dots can be modeled as diffusion in a fractal space of dimension less than two.

Motion Analysis for Short and Long Jump

Motion analysis is very essential in sport activities to enhance the performance of an athlete and to ensure the correctness of regimes. Expensive methods of motion analysis involving the use of sophisticated technology has led to limited application of motion analysis in sports. Towards this, in this paper we have integrated a lowcost method for motion analysis using three axis accelerometer, three axis magnetometer and microcontroller which are very accurate and easy to use. Seventeen male subjects performed two experiments, standing short jumps and long jumps over a wide range of take-off angles. During take-off and landing the acceleration and angles at different joints of the body are recorded using accelerometers and magnetometers, and the data is captured using Lab VIEW software. Optimum take-off angle in these jumps are calculated using the recorded data, to identify the optimum projection angle that maximizes the distance achieved in a jump. The results obtained for optimum take off angle in short jump and long jump is in agreement with those obtained using other methodologies and theoretical calculations assuming jump to be a projectile motion. The impact force (acceleration) is also analysed and is found to progressively decrease from foot to neck.

Time Series Analysis of Particle Tracking Data for Molecular Motion on the Cell Membrane

Biophysicists use single particle tracking (SPT) methods to probe the dynamic behavior of individual proteins and lipids in cell membranes. The mean squared displacement (MSD) has proven to be a powerful tool for analyzing the data and drawing conclusions about membrane organization, including features like lipid rafts, protein islands, and confinement zones defined by cytoskeletal barriers. Here, we implement time series analysis as a new analytic tool to analyze further the motion of membrane proteins. The experimental data track the motion of 40 nm gold particles bound to Class I major histocompatibility complex (MHCI) molecules on the membranes of mouse hepatoma cells. Our first novel result is that the tracks are significantly autocorrelated. Because of this, we developed linear autoregressive models to elucidate the autocorrelations. Estimates of the signal to noise ratio for the models show that the autocorrelated part of the motion is significant. Next, we fit the probability distributions of jump sizes with four different models. The first model is a general Weibull distribution that shows that the motion is characterized by an excess of short jumps as compared to a normal random walk. We also fit the data with a chi distribution which provides a natural estimate of the dimension d of the space in which a random walk is occurring. For the biological data, the estimates satisfy 1 < d < 2, implying that particle motion is not confined to a line, but also does not occur freely in the plane. The dimension gives a quantitative estimate of the amount of nanometer scale obstruction met by a diffusing molecule. We introduce a new distribution and use the generalized extreme value distribution to show that the biological data also have an excess of long jumps as compared to normal diffusion. These fits provide novel estimates of the microscopic diffusion constant. Previous MSD analyses of SPT data have provided evidence for nanometer-scale confinement zones that restrict lateral diffusion, supporting the notion that plasma membrane organization is highly structured. Our demonstration that membrane protein motion is autocorrelated and is characterized by an excess of both short and long jumps reinforces the concept that the membrane environment is heterogeneous and dynamic. Autocorrelation analysis and modeling of the jump distributions are powerful new techniques for the analysis of SPT data and the development of more refined models of membrane organization. The time series analysis also provides several methods of estimating the diffusion constant in addition to the constant provided by the mean squared displacement. The mean squared displacement for most of the biological data shows a power law behavior rather the linear behavior of Brownian motion. In this case, we introduce the notion of an instantaneous diffusion constant. All of the diffusion constants show a strong consistency for most of the biological data.

'Zigzag motion' goes in unexpected directions

In a novel 'zigzag motion' display, random dots made alternate long and short jumps, 10 mm downward and 1 mm to the right. The zigs and zags were either at right angles (differing by 90 degrees) or in opposite directions (180 degrees). The perceived direction of motion varied with the viewing distance or spatial scale. During close-up [or distant] viewing the display appeared to move in the direction of the short [or long] jumps. When the motion was stopped after 30 s, a motion aftereffect (MAE) was seen, driven by the short jumps but not the long jumps. Therefore, the perceived direction of motion was dissociated from its aftereffect. A picture rotated alternately 5 degrees clockwise (CW) and 1 degrees counterclockwise (CCW) and appeared to rotate jerkily CW. When stopped, a clockwise MAE was seen, appropriate to the small 1 degrees jumps. If the test field contained blurred, dynamic visual noise, the MAE was now CCW, appropriate to the large 5 degrees jumps; the large jumps drove the perceived motion direction and dynamic MAE, but the small jumps drove the static MAE. Winner-take-all competition between pathways tuned to fast and slow movements. Their independent adaptation gave opposite static and dynamic MAEs.

Universal Earthquake-Occurrence Jumps, Correlations with Time, and Anomalous Diffusion

Spatiotemporal properties of seismicity are investigated for a worldwide (WW) catalog and for southern California in the stationary case (SC), showing a nearly universal scaling behavior. Distributions of distances between consecutive earthquakes (jumps) are magnitude independent and show two power-law regimes, separated by jump values about 200 (WW) and 15 km (SC). Distributions of waiting times conditioned to the value of jumps show that both variables are correlated, in general, but turn out to be independent when only short or long jumps are considered. Finally, diffusion profiles are found to be independent on the magnitude, contrary to what the waiting-time distributions suggest.

Foraging behavior and diet composition of Trimma caudomaculata and Trimma caesiura (Gobiidae) on coral reefs in Okinawa, Japan

The feeding habits of two small gobies, Trimma caudomaculata and T. caesiura, were surveyed on coral reefs in Okinawa, Japan. Both species actively exhibited foraging attempts beneath overhanging reef structures during the daytime, and fed on small animals, mainly copepods. Trimma caudomaculata formed feeding schools in water columns to swallow mainly Calanoida and Harpacticoida. Trimma caesiura stayed by themselves on the reef substratum and captured mainly Harpacticoida by taking short jumps into the water column. Diet compositions of these congeneric gobies may reflect differences in their foraging behaviors and use of microhabitats.

Effects of diel vertical migration on ephippia production in Daphnia

Fish presence in experimentally simulated temperature conditions (limno-towers) led to diel vertical migration and resulted in a decrease of ephippia production in Daphnia pulicaria. Diel fluctuation of food, temperature and day length similar to those experienced by migrating Daphnia were tested in laboratory experiments with flow-through-systems. Daphnids were kept under these conditions for 15 days and the proportions of females producing an ephippium were determined. In addition, maturation time, survival to maturation, size of the first clutch and female dry weight (without eggs) on day 15 were traced. The most important factor affecting ephippia production in migrating Daphnia was photoperiod change, and when mother and embryo are exposed to alternating light conditions, these are thought to have the effect on the mother of acting as a signal to stop ephippia production. Such effects might be explained by the different sensitiveness to light intensity in females carrying an embryo and an embryo itself in broods. Fish presence forced Daphnia to stay in low-light conditions during daytime hours, to avoid attacks by fish. The Daphnia were able to check light intensity constantly by short vertical jumps above a light-threshold that was confirmed experimentally in limno-towers. The dim conditions were possibly light enough for adults to check day length, but were too dark for embryos shaded by the mother's body. Food conditions played a relatively small role in the process, and no effects of temperature on ephippia production were found. As expected, food affected the size of the first clutch, and temperature controlled the time to maturation. Photoperiod had a marginally significant influence on the time to maturation in Daphnia. A hypothesis on the role of photoperiod as the key factor for Daphnia life cyclic recurrence and other seasonal adaptations is proposed.

Plastic instabilities with propagating deformation bands in Cu–Al alloys

A multizone laser scanning extensometric technique is used to measure, in parallel with sensitive and rapid stress recording, the sudden strain avalanches and accompanying stress drops during the Portevin–Le Châtelier (PLC) plastic instabilities of type B, which are characterized by jerky propagation in successive short jumps of a deformation band along the specimen axis during deformation with constant strain rate. For the example of Cu–15 at% Al polycrystals the breakaway process for the plastic avalanches is analysed from their strain rate and temperature dependence. It is concluded that local stress concentrations are essential in addition to the dynamic-strain-ageing effect in producing the PLC effect.

Male singing behaviour and female presence in the territory in whitethroats Sylvia communis

Unmated male songbirds usually change their vocal behaviour when females enter their territories. Either the males court the females by changing the rate or pattern with which their normal long-ranging full songs are emitted, or they shift to special displays and long- or short-ranging vocalisations. In this study we quantified how female presence and behaviour affect the singing behaviour of male whitethroats. In the presence of a female the male frequently performed song flights, maybe to locate the female before it was courted, with sequences of diving-song displays. The courtship was interrupted by periods of perch songs. Female dscharp calls and short movements made the males initiate or resume courtship, whereas short horizontal jumps made the males intensify their courtship. Overall, the males changed their dual-function song activity in females' presence by emitting fewer perch songs and more flight songs. The quiet diving songs were only emitted during direct courtship of a female. The song types emitted immediately before, during, and after courtship are all highly variable, thus allowing for a quick assessment of the male's song repertoire. The courtship was also interrupted by periods of male woid calling, a call that is known to have a deterring effect on rival males. Bouts of woid calls were usually followed by song flights, again probably to locate the female that might have moved out of sight, or maybe to locate potential rival intruders. The latter was supported by an increased intrusion rate during female presence.

Jumping in frogs: assessing the design of the skeletal system by anatomically realistic modeling and forward dynamic simulation.

Comparative musculoskeletal modeling represents a tool to understand better how motor system parameters are fine-tuned for specific behaviors. Frog jumping is a behavior in which the physical properties of the body and musculotendon actuators may have evolved specifically to extend the limits of performance. Little is known about how the joints of the frog contribute to and limit jumping performance. To address these issues, we developed a skeletal model of the frog Rana pipiens that contained realistic bones, joints and body-segment properties. We performed forward dynamic simulations of jumping to determine the minimal number of joint degrees of freedom required to produce maximal-distance jumps and to produce jumps of varied take-off angles. The forward dynamics of the models was driven with joint torque patterns determined from inverse dynamic analysis of jumping in experimental frogs. When the joints were constrained to rotate in the extension-flexion plane, the simulations produced short jumps with a fixed angle of take-off. We found that, to produce maximal-distance jumping, the skeletal system of the frog must minimally include a gimbal joint at the hip (three rotational degrees of freedom), a universal Hooke's joint at the knee (two rotational degrees of freedom) and pin joints at the ankle, tarsometatarsal, metatarsophalangeal and iliosacral joints (one rotational degree of freedom). One of the knee degrees of freedom represented a unique kinematic mechanism (internal rotation about the long axis of the tibiofibula) and played a crucial role in bringing the feet under the body so that maximal jump distances could be attained. Finally, the out-of-plane degrees of freedom were found to be essential to enable the frog to alter the angle of take-off and thereby permit flexible neuromotor control. The results of this study form a foundation upon which additional model subsystems (e.g. musculotendon and neural) can be added to test the integrative action of the neuromusculoskeletal system during frog jumping.

Female behaviour affects male courtship in whitethroats, Sylvia communis: an interactive experiment using visual and acoustic cues

Unmated male whitethroats court females with a special display in which the male dives towards the female while singing a quiet and complex song, the diving song. Observations of natural interactions suggest that females can affect males' courtship behaviour by making dscharp-calls or ze-calls and by making short jumps towards the diving males. We tested this in an interactive experiment where jumps and calls were presented in different combinations to unmated territorial males. Jumps were presented by means of a stuffed female mounted on a remotely controlled device, and calls were played back from a speaker placed beneath the stuffed female. Female calls and jumps had a strong but differential effect on male courtship. Playback of dscharp-calls attracted the attention of males and hence caused them to perform courtship sooner and jumps increased the number of diving songs, whereas ze-calls resulted in more males attempting copulation with the stuffed female.

Dynamics of n-Butane−Methane Mixtures in Silicalite, Using Quasielastic Neutron Scattering and Molecular Dynamics Simulations

The transport of n-butane−methane mixtures in the zeolite silicalite was studied using molecular dynamics simulations and quasielastic neutron scattering experiments over a range of loadings and compositions at 200 K. Self-diffusivities are seen to decrease monotonically with loading of either species. Self-diffusivity values calculated from the dynamics simulations are in excellent agreement with the experimental measurements from quasielastic neutron scattering if one takes into account the errors associated with both techniques. We also studied the detailed dynamical behavior of the system. The dependence on the wave vector of the half-width at half-maximum of the incoherent dynamic structure factor, describing self-correlations in the motion of sorbate molecules, is indicative of a jump diffusion process. By monitoring and analyzing the molecular motion in the simulation, we confirmed that diffusion takes place through successive jumps between the interiors of adjacent channel segments. Precise and quantitative calculations mapping the MD trajectories onto a coarse-grained jump model reveal mechanistic aspects of the motion. Distributions of jump lengths and rate constants are accumulated for the various jump types executed by each sorbate species. Jump lengths are widely distributed between 0 and 15 Å, the mean jump length being a decreasing function of the loading. The mean time between jumps is actually smaller at higher occupancies, because there short jumps prevail, occurring back and forth in a highly correlated fashion.