Sling Shot Research Articles

The Effects of the "Sling Shot" Device on Bench Press Performance, Mechanical Properties of Muscle, and Movement Kinematics.

Wojdała, G and Krzysztofik, M. The effects of the "sling shot" device on bench press performance, mechanical properties of muscle, and movement kinematics. J Strength Cond Res 37(4): 780-786, 2023-This study aimed to evaluate the influence of the sling shot support device at various external loads and intensities of effort, taking into account acute changes in power performance, mechanical muscle properties, and bench press kinematics. For this purpose, 12 resistance-trained men (age: 27.1 ± 4.2 years, body mass: 90.3 ± 16.9 kg, bench press [BP] 1 repetition maximum [1RM]: 112.7 ± 23.1 kg) (resistance training experience: 6.9 ± 3.8 years) participated in the study. Each subject completed 2 experimental sessions that differed in the use of the sling shot (SS) or nonuse (CONT) of the SS and an appropriate external load. The 2 experimental sessions consisted of the 1RM test, 3 sets of 2 repetitions of BP with the load increased in each set (50-70-90% 1RM), and a fourth set of the BP efforts to muscle failure with a 70% 1RM load. Before and after each set, the changes in triceps brachii oscillation frequency and stiffness were assessed by means of myotonometry. Results indicated a significant main effect of the SS to increase peak power ( p < 0.0001, η 2 = 0.733). Furthermore, a significantly higher 1RM (129 ± 26 vs. 113 ± 23 kg, p < 0.001, effect size [ES]: 0.63), number of repetitions (15 ± 3 vs. 13 ± 2, p = 0.013, ES: 0.76), and time under tension (34 ± 10 vs. 29 ± 6 seconds, p = 0.017, ES: 0.59) were found during the set to failure for SS in comparison to the CONT condition. Moreover, there was a significant main effect of time to increase oscillation frequency ( p = 0.001; η 2 = 0.666) and stiffness ( p = 0.002; η 2 = 0.613) from pre- to postset measure. In addition, the main effect of the side ( p = 0.034; η 2 = 0.348) was reported to show higher stiffness on the dominant than on the nondominant side in the CONT condition. The results suggest that an independent 1RM measurement and a correspondingly higher workload are required to take full advantage of the SS device. Moreover, the SS can also be used successfully to increase training volume and the involvement of nondominant limbs during a bench press.

A Comparison of Electromyographic Inter-Limb Asymmetry During a Standard Versus a Sling Shot Assisted Bench Press Exercise.

The objective of this study was to compare peak surface electromyography (sEMG) activity of selected muscles along with inter-limb asymmetries between a control (CONT) and a Sling shot assisted (SS) bench press exercise. Ten resistance-trained males with at least three-year experience in resistance training (22.2 ± 1.9 years, 88.7 ± 11.2 kg, 179.5 ± 4.1 cm, bench press one-repetition maximum (1RM) = 127.3 ± 25.9 kg) performed the flat bench press exercise under two conditions at selected loads (85% and 100% of 1RM assessed without the SS). Peak sEMG amplitude of triceps brachii, pectoralis major, and anterior deltoid was recorded for the dominant and the non-dominant side of the body during each attempt. The comparison between the dominant and the non-dominant side was carried out using the limb symmetry index (LSI(%) = (2*(XR - XL)/(XR + XL))*100%) where XR = values of the right side and XL = values of the left side. There was a main effect of condition (p = 0.004; η2 = 0.64) and the load (p = 0.004; η2 = 0.63) for the triceps brachii LSI in parallel with a main effect of condition (p = 0.003; η2 = 0.42) for the anterior deltoid LSI. Post hoc analysis for the main effect of condition showed significant differences in the LSI between the CONT and SS conditions for the triceps brachii (p = 0.003; 1.10% vs. -8.78%) as well as for the anterior deltoid muscles (p = 0.03; 12.91% vs. 9.23%). The results indicate that the assistance of the Sling shot significantly affects the sEMG activity pattern on both the dominant and non-dominant sides of the body while influencing inter-limb asymmetries.

Roosting ecology and morphometric analysis of Pteropus medius (Indian flying fox) in Lower Dir, district, Pakistan.

The present study was conducted to explore morphometric variations of Pteropus medius (the Indian flying fox) and the roosting trees in Lower Dir, Pakistan. The bats were captured from Morus alba, Morus nigra, Brousonetia papyrifera, Pinus raxburghii, Hevea brasiliensis, Platanus orientalis, Populous nigra, Melia azedarach, Eucalyptus camaldulensis and Grevillea robusta through sling shot and mess net methods. A total of 12 bats were studied for the differential morphological features based on age and sex. Male bats were recorded higher in weight than females. The variations were found in body mass (821.1±34.65gm), circumference of body with wings (25.43±0.39cm), wingspan (112.58±1.90cm), Body length (20.73±0.68cm), Snout length (3.42±0.04cm), Eye length (1.45±0.033cm), Length of ear (3.56±0.05cm), Width of ear (2.46±0.04cm), Length b/w ear (5.51±0.11cm), Circumference of neck (12.23±0.24cm), Circumference of body without wings (18.68±0.31cm), Arm wing length (23.2±1.03cm), Length of thumb (5.43±0.1cm), Length of nail (1.89±0.05cm), Hand wing length (29.1±0.51cm), Maximum width of wing (21.03±0.68cm), Length b/w tip of wing to 5th digit (29.39±0.30cm), Length b/w 5th digit to foot (22.97±1.09cm), Length b/w feet (18.31±0.74cm) and Length of foot claw (4.23±0.05cm). This study was designed for analysis of external morphological variations for P. medius (the Indian flying fox) that may help in identification of these bats and their roosting sites.

Dry eye disease - are we underselling it? An epidemic in the offing and future management trends

Dry eye definition and management has seen a complete overhaul over the past two decades. With increasing life style changes the incidence of DED has exponentially increased and it’s not relevant only to the developed world anymore. The earlier thought demography of patients susceptible for dry eye has also changed considerably. In India the prevalence of dry eye ranges from 18.4% to 40.8%. This increasing incidence of DED has provided a sling shot for many pharmaceutical industry leaders to come up with novel innovative treatment methodologies for holistic management of dry eye disease. In our brief communication we look at the history of dry eye diagnosis and management and future treatment options available for treating clinicians to tackle the epidemic of DED.

Impact of the "Sling Shot" Supportive Device on Upper-Body Neuromuscular Activity during the Bench Press Exercise.

The aim of this study was to compare the muscle activity between the sling shot assisted (SS) and control (CONT) flat barbell bench press for selected external loads of 70%, 85%, 100% one-repetition maximum (1RM). Ten resistance-trained men participated in the study (age = 22.2 ± 1.9 years, body mass = 88.7 ± 11.2 kg, body height = 179.5 ± 4.1, 1RM in the bench press = 127.25 ± 25.86 kg, and strength training experience = 6 ± 2.5 years). Evaluation of peak muscle activity of the dominant body side was carried out using surface electromyography (sEMG) recorded for the triceps brachii, pectoralis major, and anterior deltoid during each attempt. The three-way repeated measure ANOVA revealed statistically significant main interaction for condition x muscle group (p < 0.01; η2 = 0.569); load x muscle group (p < 0.01; η2 = 0.709); and condition x load (p < 0.01; η2 = 0.418). A main effect was also observed for condition (p < 0.01; η2 = 0.968); load (p < 0.01; η2 = 0.976); and muscle group (p < 0.01; η2 = 0.977). The post hoc analysis for the main effect of the condition indicated statistically significant decrease in %MVIC for the SS compared to CONT condition (74.9 vs. 88.9%MVIC; p < 0.01; ES = 0.39). The results of this study showed that using the SS significantly affects the muscle activity pattern of the flat bench press and results in its acute decrease in comparison to an equal load under CONT conditions. The SS device may be an effective tool both in rehabilitation and strength training protocols by increasing stability with a reduction of muscular activity of the prime movers.

The ‘Sling Shot’ increased the maximum number of repetitions in the barbell bench press in men with different resistance training experience

PurposeThe study examined if the elastic device named Sling Shot could increase the maximum number of repetitions (MNR) and diminish the mean repetition duration in men with different resistance training experience while performing the bench press exercise in multiple sets.MethodsOverall, 22 men were grouped depending on their resistance training experience. The most experienced group (MEG; 11 men, 65.45 ± 26.27 months of training experience) and the less experienced group (LEG; 11 men, 3.09 ± 2.07 months of training experience) performed 3 sets at 80% of the 1-repetition maximum test as fast as possible, with 2-min rest, of the barbell bench press exercise with and without the Sling Shot. Two 3-way ANOVA tests, with α = 0.05, were used to compare the MNR and mean repetition duration in inter- and intra-group comparisons across the sets.ResultsThe Sling Shot increased the MNR in the 2 groups throughout the 3 sets. The increase was 50.5%, 65.4%, and 43.8% in the MEG group and 120%, 68.4%, and 43.3% in the LEG group for the 1&lt;sup&gt;st&lt;/sup&gt;, 2&lt;sup&gt;nd&lt;/sup&gt;, and 3&lt;sup&gt;rd&lt;/sup&gt; sets, respectively. However, there was no difference in the MNR between groups when the Sling Shot was used. Additionally, both groups performed the repetitions with a shorter mean duration with the Sling Shot than without it. No difference was observed between the groups.ConclusionsRegardless of training experience, the Sling Shot constitutes an alternative for increasing the MNR and decreasing the mean repetition duration in multiple sets.

Water balloon-induced orbital fracture in an aviator

BackgroundOrbital fractures are common injuries found in facial trauma. Typical etiologies of orbital fractures include motor vehicle collisions and assault. We report the case of a 32-year-old male who suffered an orbital fracture from a water balloon. Additionally, we describe the aeromedical complications that may result from this injury. Finally, we attempt to answer the question of when a patient may return to flying after sustaining such an injury through review of the literature.Case presentationA 32-year-old male pilot with the United States Air Force was at an outdoor event with his unit when he was struck with a water balloon launched from a sling shot into his left orbit. Shortly afterwards, he had an onset of subcutaneous emphysema and was escorted to a nearby Emergency Department. Computed tomography identified an orbital fracture with associated orbital and subcutaneous emphysema. The patient was evaluated by a plastic surgeon and was determined not to be a surgical candidate. Four weeks later, he returned to flying status.ConclusionsWater balloons are thought to be safe and harmless toys. However, when coupled with slingshots, water balloons can become formidable projectiles capable of significant orbital injury including orbital fractures. These injuries are concerning to aviators, as the most common sites for fractures of the orbit are the thin ethmoid and maxillary bones adjacent to the sinuses. At altitude, gases in the sinuses may expand and enter the orbit through these fractures, which may suddenly incapacitate the flyer. It is important for flight surgeons to identify and assess these individuals to determine suitability for flying.

Building an “Escape Portal” with Tethers Fixed in Asteroids

The main idea of this paper is to propose the construction of an “Escape Portal” to send a spacecraft to the exterior planets, or even to make it escape from the Solar System, using a Tethered Sling Shot Maneuver (TSSM) with an asteroid. The construction of this portal allows an unlimited number of maneuvers with the same tether, which is very interesting when considering a possible use for small satellites. This structure would be formed by a tether that remains fixed in an asteroid. At the other end of the tether, a large net is fixed, such that the only action required from the spacecraft to make the TSSM is to hit the net. The net can have a mechanism to open a passage to release the spacecraft when the desired rotation is obtained. This technique would avoid some of the problems that appear when assuming that the spacecraft needs to carry a tether on board that would be released to hit the asteroid just before the maneuver.

Orthodontic extrusion of Ellis Class VIII fracture of maxillary lateral incisor – The sling shot method

The aim of this paper is to evaluate the efficacy of forced extrusion using the sling shot elastic. A 21 year adult patient reported with an Ellis Class VIII fracture of the maxillary right lateral incisor. Root canal treatment followed by a fiber reinforced composite post was placed and core build up was done. A metal button was bonded to the tooth. Begg brackets were placed from the second premolar on one side to the second premolar on the opposite side. 0.016″ × 0.025″ stainless steel was placed in ribbon mode. The ligature wire was placed as a sling shot from the button on the fractured tooth to the two adjacent teeth. 4 mm of extrusion was achieved and there was no evidence of root resorption. Forced extrusion was achieved in four months. The sling shot method is a very effective method of ligation. Light forces are delivered over a long duration with definitive results as compared to the inconsistent force delivery with conventional extrusion mechanics.

Hop, skip, jump, or massive leap

Biomechanics In biological and engineered systems, an inherent trade-off exists between the force and velocity that can be delivered by a muscle, spring, or combination of the two. However, one can amplify the maximum throwing power of an arm by storing the energy in a bow or sling shot with a latch mechanism for sudden release. Ilton et al. used modeling to explore the performance of motor-driven versus spring-latch systems in engineering and biology across size scales. They found a range of general principles that are common to animals, plants, fungi, and machines that use elastic structures to maximize kinetic energy. Science , this issue p. [eaao1082][1] [1]: /lookup/doi/10.1126/science.aao1082

The principles of cascading power limits in small, fast biological and engineered systems.

Mechanical power limitations emerge from the physical trade-off between force and velocity. Many biological systems incorporate power-enhancing mechanisms enabling extraordinary accelerations at small sizes. We establish how power enhancement emerges through the dynamic coupling of motors, springs, and latches and reveal how each displays its own force-velocity behavior. We mathematically demonstrate a tunable performance space for spring-actuated movement that is applicable to biological and synthetic systems. Incorporating nonideal spring behavior and parameterizing latch dynamics allows the identification of critical transitions in mass and trade-offs in spring scaling, both of which offer explanations for long-observed scaling patterns in biological systems. This analysis defines the cascading challenges of power enhancement, explores their emergent effects in biological and engineered systems, and charts a pathway for higher-level analysis and synthesis of power-amplified systems.

Dido, Queen of Carthage by Globe Young Players (review)

Reviewed by: Dido, Queen of Carthageby Globe Young Players Miranda Fay Thomas Dido, Queen of CarthagePresented by the Globe Young Playersat the Sam Wanamaker Playhouse, Shakespeare’s Globe, London, England. April 9–18, 2015. Directed by Jacqui Somerville. Design by Mia Fiodquist. Music composed by Olly Fox. Musical Direction by Rob Millett. Choreography by Paul Harris. With Guy Amos (Aeneas), Alexander Clarke (Jupiter/Sergestus), Benjamin Clarke (Cupid), Martha Lily Dean (Ganymede/Ilioneus), Isaac Deayton (Achates), Ed Easton (Ascanius/Carthaginian Lord), Brogan Gilbert (Nurse/Carthaginian Lady), Jasmine Jones (Dido), Ben Lynn (Iarbus), Joseph Marshall (Cloanthus), Sekela Nancy Ngamilo (Anna), Yasmin Prince (Juno/Hermes), and Tamla Tutankhamun (Venus). The Sam Wanamaker Playhouse’s (SWP’s) second season closed, as its first season had done, with an effort from the Globe Young Players. Featuring the same cast of young actors as last year’s The Malcontent, this latest offering showed a pleasing level of maturation within the company while still retaining a sense of fun and play, despite the play’s generic expectation of tragedy. Clearly growing in confidence within the intimate, candlelit space of the SWP, the youngsters’ performance of Marlowe’s tragedy was, overall, far more successful than their first endeavor. This was largely due to the direction of Jacqui Somerville, who enabled the young actors to play on their youthfulness rather than trying to hide it. As we awaited the play’s beginning, the usual architecture and lighting of the SWP were augmented by the sight of grape vines creeping up the pillars to the left and right of the stage, indicating a more classical source than that of last year’s satirical comedy. All three stage doors were left ajar, tantalizing the audience’s gaze with glittering things in the dark beyond. The performance itself began with the young cast emerging out of the darkness, attired in the grays of school uniform complimented by more playful materials of silver and sequins. One boy, who we later discovered to be Cupid (Benjamin Clarke), had safety pins arranged in a pattern of wings on the back of his blazer, and a sling shot rather than a bow. The production consciously evoked the idea of a school play, and chose to acknowledge the youth of the actors and use it to their advantage. Seen in this light, the fake moustaches worn by the children were witty rather than twee. The musical instruments, from oboes to trumpets, played by the cast during the opening revealed that, unlike in many a school production, some of these youthful players had talent and nous beyond their years. [End Page 531] The direction by Jacqui Somerville was clever and sensitive, with the actors encouraged to make imaginative use of the space. Music composed by Olly Fox was deployed subtly and aptly, and helped unify the production, with chimes used to accompany the gods and goddesses as they executed their powers. The costumes, designed by Mia Fiodquist, were some of the most consistent seen at the SWP this season, with the Trojans entering in swish half capes, camouflage pants, and caps with feathers. They also had mud on their shins, and there was a sense of touching ambivalence as to whether the earth stains were redolent of the toil the soldiers had endured or the playground scrapes in which the children might have been embroiled. Jasmine Jones and Guy Amos more than justified their casting as Dido and Aeneas. Jones, in particular, had real stage presence as the Queen of Carthage: her regal orange satin gown embellished with shells, beads, and sequins supported her impressive sense of gravitas (Fig.12). Amos too showed increasing maturity in his portrayal of the Trojan hero. Aeneas’s woeful tale of Troy speech (see Marlowe, The Complete Plays, eds. Romany and Lindsey [Penguin, 2003], 2.1.121) is a perfect set piece for a young actor, and clearly written for a rising star capable of staring powerfully into the middle distance. Yet despite their ability to play beyond their years, the chemistry of the two remained enjoyably teenaged. Dido’s line, “I love thee not. / And yet I hate thee not” (3.1.170–71) came across as delightfully...

Times Are Changing

I have always felt that my job as a professor was to sweep the path in front of my graduate students and shoot them out of a sling shot. That philosophy has worked well, resulting in many today bei...

Inelastic collisions of solitary waves in anisotropic Bose–Einstein condensates: sling-shot events and expanding collision bubbles

We study experimentally and theoretically the dynamics of apparent dark soliton stripes in an elongated Bose–Einstein condensate. We show that for the trapping strengths corresponding to our experimental setup, the transverse confinement along one of the tight directions is not strong enough to arrest the formation of solitonic vortices or vortex rings. These solitonic vortices and vortex rings, when integrated along the transverse direction, appear as dark soliton stripes along the longitudinal direction thereby hiding their true character. The latter significantly modifies the interaction dynamics during collision events and can lead to apparent examples of inelasticity and what may appear experimentally even as a merger of two dark soliton stripes. We explain this feature by means of the interaction of two solitonic vortices leading to a sling shot event with one of the solitonic vortices being ejected at a relatively large speed. Furthermore we observe expanding collision bubbles which consist of repeated inelastic collisions of a dark soliton stripe pair with an increasing time interval between collisions.

Secondary glaucoma as a result of a sling shot accident, diagnosed half a century later

Secondary glaucoma following blunt trauma is relatively uncommon in regular optometric practice. Onset of this type of glaucoma may occur within weeks, but may also be delayed several decades. This case report presents a 57 year old male who, 48 years ago, suffered a sling shot accident yet was only recently diagnosed with traumatic glaucoma in his left eye. The trauma caused severely reduced vision in his left eye but, aside from this, the patient did not report any eye- or vision problems and he had never had an eye examination as an adult. He successfully wore ready-made glasses for near work. While all findings were normal in his right eye, his left eye showed reduced vision, inferionasal iridodialysis, angle recession, increased intraocular pressure and heavily excavated optic nerve head. The patient was referred to an ophthalmologist who confirmed unilateral glaucoma. The case report reviews situations where secondary glaucoma from blunt trauma may occur, which ocular signs might be present and which ocular examinations should be undertaken. Further, the importance of following up patients with ocular trauma is discussed.

The Architectural Design Rules of Solar Systems Based on the New Perspective

In this paper I present a new perspective of the birth and evolution of Planetary Systems. This new perspective presents an all encompassing and self consistent Paradigm of the birth and evolution of the solar systems. In doing so it redefines astronomy and rewrites astronomical principles. Kepler and Newton defined a stable and non-evolving elliptical orbits. While this perspective defines a collapsing or expanding spiral orbit of planets except for Brown Dwarfs. Brown Dwarfs are significant fraction of the central star. Hence they rapidly evolve from non-Keplerian state to the end point which is a Keplerian state where it is in stable elliptical orbits. On the basis of the Lunar Laser Ranging Data released by NASA on the Silver Jubilee Celebration of Man’s Landing on Moon on 21st July 1969–1994, theoretical formulation of Earth-Moon tidal interaction was carried out and Planetary Satellite Dynamics was established. It was found that this mathematical analysis could as well be applied to Star and Planets system and since every star could potentially contain an extra-solar system, hence we have a large ensemble of exo-planets to test our new perspective on the birth and evolution of solar systems. Till date 403 exo-planets have been discovered in 390 extra-solar systems by radial velocity method, by transiting planet method, by gravitational lensing method, by direct imaging method and by timing method. I have taken 12 single planet systems, four Brown Dwarf—Star systems and two Brown Dwarf pairs. Following architectural design rules are corroborated through this study of exo-planets. All planets are born at inner Clarke’s Orbit what we refer to as inner geo-synchronous orbit in case of Earth-Moon System. The inner Clarke’s Orbit is an orbit of unstable equilibrium. By any perturbative force such as cosmic particles or radiation pressure, the planet gets tipped long of aG1 or short of aG1. Here aG1 is inner Clarke’s Orbit. If planet is long of aG1 then it is said to be in extra-synchronous orbit. Here Gravitational Sling Shot effect is in play. In gravity assist planet fly-by maneuver in space flights, gravitational sling shot is routinely used to boost the space craft to its destination. The exo-planet can either be launched on death spiral as CLOSE HOT JUPITERS or can be launched on an expanding spiral path as the planets in our Solar System are. In death spiral, exo-planet less than 5 mJ will get pulverized and vaporized in close proximity to the host star. If the mass is between 5 and 7.5 mJ then it will be partially vaporized and partially engulfed by the host star and if it is greater than 7.5 mJ, then it will be completely ingested by the host star. In the process the planet will deposit all its material and angular momentum in the Host Star. This will leave tell-tale imprints of ingestion: in such cases host Star will have higher 7Li, host star will become a rapidly rotating progenitor and the host star will have excess IR. All these have been confirmed by observations of Transiting Planets. It was also found that if the exo-planet are significant fraction of the host star then those exo-planets rapidly migrate from aG1 to aG2 and have very short Time Constant of Evolution as Brown Dwarfs have. But if exo-planets are insignificant fraction of the host star as our terrestrial planets are then they are stay put in their original orbit of birth. By corollary this implies that Giant exo-planets reach nearly Unity Evolution Factor in a fraction of the life span of a solar system. This is particularly true for brown dwarfs orbiting main sequence stars. In this study four star systems hosting Brown Dwarfs, two Brown Dwarf pairs and 12 extrasolar systems hosting Jupiter sized planets are selected. In Brown Dwarfs evolution factor is invariably UNITY or near UNITY irrespective of their respective age and Time Constant of Evolution is very short of the order of year or tens of years. In case of 12 exo-planets system with increasing mass ratio evolution factor increases and time constant of evolution shortens from Gy to My though there are two exceptions. TW Hydrae is a special case. This Solar System is newly born system which is only 9 million years old. Hence its exo-planet has just been born and it is very near its birth place just as predicted by my hypothesis. In fact it is only slightly greater than aG1. This vindicates our basic premise that planets are always born at inner Clarke’s Orbit. This study vindicates the design rules which had been postulated at 35th COSPAR Scientific Assembly in 2004 at Paris, France, under the title “New Perspective on the Birth & Evolution of Solar Systems”.

Spontaneous and artificial generation of sheared-flow in oblate FRCs in TS-3 and 4 FRC Experiments

Spontaneous formation of toroidal flow was measured for the first time in oblate field-reversed configurations (FRCs) produced in TS-3 and TS-4 experiments. The toroidal ion flow (Vi ≈ 10 km s−1) was found to peak around the magnetic axis, indicating that the FRC had a peaked ion current in sharp contrast to its hollow electric current. The peaked ion flow also indicated the formation of high flow shear inside the separatrix. The toroidal flow was observed to deform the magnetic field lines of the FRC, producing bipolar toroidal field profile. In high-s FRC (averaged number of ion gyro-radii in the separatrix: `s' = 4.5) with slow flow, its n = 1 mode kept growing, causing collapse of the whole configuration. However, in low-s FRC (s = 3) with fast flow, the rotating n = 2 mode (saturated) became dominant after n = 1 mode saturation. The spontaneous formation of flow-shear possibly transformed the n = 1 mode into the n = 2 mode, suggesting a new sheared-flow stabilization of the n = 1 mode. The flow-shear was also generated artificially using the `sling shot' effect of the counterhelicity reconnection. The n = 1 and 2 mode amplitudes were reduced to (1/5)–(1/10) due to the generated flow-shear. A new method for continuous sheared-flow generation was proposed for stabilization and heating of FRC by the use of intermittent merging of spheromaks with opposing toroidal field.

Near-Earth Asteroid Missions Using Tether Sling Shot Assist

A new space exploration technique, called tether sling shot assist, is examined for near-Earth asteroid sample return missions. A spacecraft eying near an asteroid can attach itself to the asteroid using a space tether and an anchor device. After attachment, thevelocity vector ofthespacecraft relative totheasteroid canberotated, thereby modifying its heliocentric velocity. The link to the anchoring device can then be severed, and the spacecraft can reel the tether back for reuse. A simplieed analysis is presented of the problem, and the technical issues related to this maneuver are discussed. A trajectory analysis software is also developed and implemented to determine the possible trajectories of near-Earth asteroid sampling missions. For each trajectory, the strengths and weaknesses of different mission scenarios are highlighted. When combined with chemical propulsion, tether sling shot assist leads to very signiecant payload mass gains over conventional all-chemical propulsion systems.

MHD simulations of magnetotail dynamics

Resistive MHD simulations of large‐scale magnetotail dynamics demonstrate that the same unstable mode causes plasmoid formation and ejection into the far tail and dipolarization and the formation of the substorm current wedge in the inner tail, consistent with the neutral line model of substorms. However, they have also modified some aspects of the model and added details that could not easily be inferred without the self‐consistent approach. We review recent results that include the externally driven formation of a thin current sheet in the near tail, which eases the onset of instability and leads to a faster dynamic evolution. In contrast to earlier expectations, the field‐aligned current generation and diversion takes place in the inner tail earthward of the reconnection site, resulting from shear and diversion of the earthward flow caused by reconnection farther out. Dipolarization starts most pronounced in the tail‐dipole transition region, propagating both tailward and flankward. Strong electric fields and plasma heating also are most prominent in the inner tail. Three‐dimensional simulations without mirror symmetries have generalized the picture of plasmoid formation and ejection, demonstrating a tangled geometry of helical flux ropes with different connections that change increasingly from the Earth to the magnetosheath. The interconnection with the magnetosheath may also play a role in generating plasmoid flux ropes with strong core fields. Mass, energy, and momentum gain of plasmoids results mainly from the accumulation of already accelerated plasma rather than from a sling shot effect acting on the entire plasmoid.

Federation Dentaire Internationale (F. D.I.)

The aim of this paper is to evaluate the efficacy of forced extrusion using the sling shot elastic. A 21 year adult patient reported with an Ellis Class VIII fracture of the maxillary right lateral incisor. Root canal treatment followed by a fiber reinforced composite post was placed and core build up was done. A metal button was bonded to the tooth. Begg brackets were placed from the second premolar on one side to the second premolar on the opposite side. 0.016″ × 0.025″ stainless steel was placed in ribbon mode. The ligature wire was placed as a sling shot from the button on the fractured tooth to the two adjacent teeth. 4 mm of extrusion was achieved and there was no evidence of root resorption. Forced extrusion was achieved in four months. The sling shot method is a very effective method of ligation. Light forces are delivered over a long duration with definitive results as compared to the inconsistent force delivery with conventional extrusion mechanics.