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Concept: Specific force


Current predictions of extinction risks from climate change vary widely depending on the specific assumptions and geographic and taxonomic focus of each study. I synthesized published studies in order to estimate a global mean extinction rate and determine which factors contribute the greatest uncertainty to climate change-induced extinction risks. Results suggest that extinction risks will accelerate with future global temperatures, threatening up to one in six species under current policies. Extinction risks were highest in South America, Australia, and New Zealand, and risks did not vary by taxonomic group. Realistic assumptions about extinction debt and dispersal capacity substantially increased extinction risks. We urgently need to adopt strategies that limit further climate change if we are to avoid an acceleration of global extinctions.

Concepts: Risk, Climate, Classical mechanics, Acceleration, Rate, Global warming, Biogeography, Specific force


OBJECTIVE Although 70% of football players in the United States are youth players (6-14 years old), most research on head impacts in football has focused on high school, collegiate, or professional populations. The objective of this study was to identify the specific activities associated with high-magnitude (acceleration > 40g) head impacts in youth football practices. METHODS A total of 34 players (mean age 9.9 ± 0.6 years) on 2 youth teams were equipped with helmet-mounted accelerometer arrays that recorded head accelerations associated with impacts in practices and games. Videos of practices and games were used to verify all head impacts and identify specific drills associated with each head impact. RESULTS A total of 6813 impacts were recorded, of which 408 had accelerations exceeding 40g (6.0%). For each type of practice drill, impact rates were computed that accounted for the length of time that teams spent on each drill. The tackling drill King of the Circle had the highest impact rate (95% CI 25.6-68.3 impacts/hr). Impact rates for tackling drills (those conducted without a blocker [95% CI 14.7-21.9 impacts/hr] and those with a blocker [95% CI 10.5-23.1 impacts/hr]) did not differ from game impact rates (95% CI 14.2-21.6 impacts/hr). Tackling drills were observed to have a greater proportion (between 40% and 50%) of impacts exceeding 60g than games (25%). The teams in this study participated in tackling or blocking drills for only 22% of their overall practice times, but these drills were responsible for 86% of all practice impacts exceeding 40g. CONCLUSIONS In youth football, high-magnitude impacts occur more often in practices than games, and some practice drills are associated with higher impact rates and accelerations than others. To mitigate high-magnitude head impact exposure in youth football, practices should be modified to decrease the time spent in drills with high impact rates, potentially eliminating a drill such as King of the Circle altogether.

Concepts: United States, Shock, Drill, Circle, Acceleration, Impact factor, American football, Specific force


We quantified the acceleration and high-velocity running of elite Australian soccer players. We hypothesised that high-intensity activity would be underestimated when excluding acceleration during match analysis given its high metabolic demand and occurrence at low velocities. Player movements were observed from 29 players (forwards and central and wide defenders and midfielders) during domestic Australian competition using 5-Hz global positioning system. Effort occurrence were determined for high-velocity running, sprinting and maximal accelerations. The commencement and final velocity of maximal accelerations were also identified. Players undertook an 8~fold greater number of maximal accelerations than sprints per game (65±21 vs. 8±5). Of maximal accelerations ~98% commenced from a starting velocity lower than what would be considered high-velocity running while ~85% did not cross the high-velocity running threshold. The number of efforts performed in all categories were position dependent (P<0.001). Wide defenders performed more maximal accelerations (P<0.006) and central defenders and midfielders performed less sprints compared to all other positions (P<0.02). Maximal accelerations are frequently undertaken during a match often occurring at low velocities. Excluding maximal accelerations in match analysis research may underestimate the amount of high-intensity movements undertaken. Additionally positional differences in high-intensity movements should be accounted for when developing specific conditioning drills.

Concepts: General relativity, Acceleration, Velocity, Kinematics, Global Positioning System, Motion, Global navigation satellite system, Specific force


Controlling for multiple hypothesis tests using standard spike resampling techniques often requires prohibitive amounts of computation. Importance sampling techniques can be used to accelerate the computation. The general theory is presented, along with specific examples for testing differences across conditions using permutation tests and for testing pairwise synchrony and precise lagged-correlation between many simultaneously recorded spike trains using interval jitter.

Concepts: Statistics, Sample size, Sampling, General relativity, Classical mechanics, Acceleration, Particle filter, Specific force


We investigated whether acoustic variation of musical properties can analogically convey descriptive information about an object. Specifically, we tested whether information from the temporal structure in music interacts with perception of a visual image to form an analog perceptual representation as a natural part of music perception. In Experiment 1, listeners heard music with an accelerating or decelerating temporal pattern, and then saw a picture of a still or moving object and decided whether it was animate or inanimate - a task unrelated to the patterning of the music. Object classification was faster when musical motion matched visually depicted motion. In Experiment 2, participants heard spoken sentences that were accompanied by accelerating or decelerating music, and then were presented with a picture of a still or moving object. When motion information in the music matched motion information in the picture, participants were similarly faster to respond. Fast and slow temporal patterns without acceleration and deceleration, however, did not make participants faster when they saw a picture depicting congruent motion information (Experiment 3), suggesting that understanding temporal structure information in music may depend on specific metaphors about motion in music. Taken together, these results suggest that visuo-spatial referential information can be analogically conveyed and represented by music and can be integrated with speech or influence the understanding of speech.

Concepts: Perception, Classical mechanics, Pattern, Acceleration, Kinematics, Euclidean vector, Newton's laws of motion, Specific force


Management of an infratemporal fossa abscess (IFA), which is a specific form of severe and advanced deep fascial space infection (DFI), is based mainly on traditional methods. The purpose of this study was to investigate the role of mandibular coronoidectomy in accelerating IFA healing.

Concepts: General relativity, Classical mechanics, Acceleration, Mandibular nerve, Specific force, Infratemporal fossa, Auriculotemporal nerve, Otic ganglion


Precision medicine in cancer care uses specific information about a person’s tumor to help diagnose, plan treatment, prognosticate, and surveil throughout the cancer trajectory. Applications exist for cancer prevention, early detection, cancer treatment, and supportive care. Several national initiatives (e.g., National Cancer Moonshot Initiative) support these efforts to accelerate this science forward.

Concepts: Cancer, Oncology, Tumor, Classical mechanics, Acceleration, Technical support, Specific force, Direct democracy


Since postnatal identification of accelerated idioventricular rhythm (AIVR) is essentially based on specific electrocardiographic patterns, its prenatal diagnosis is challenging and its genuine incidence undetermined. Therefore the objectives of this study are: 1) To evaluate the performance of specific ultrasonographic approaches in intrauterine identification of cardiocirculatory events linked to electrocardiographic signs of AIVR, including its left or right ventricular origin, and 2) To assess the prenatal prognosis of the arrhythmia.

Concepts: Pregnancy, Childbirth, Embryo, Medical diagnosis, Classical mechanics, Acceleration, Prenatal diagnosis, Specific force


A novel concept that the conformational switch of cytosine-rich DNA can accelerate the release of drug from DNA-capped nanovehicles is rationally devised. Our present strategy can greatly extend the potential usages of DNA molecules with specific sequences as conformational switch-controlled devices.

Concepts: DNA, Physical quantities, Classical mechanics, Acceleration, Kinematics, Specific force


According to the “punctum fixum-punctum mobile model” that was introduced in prior studies, for generation of the most effective intentional acceleration of a body part the intersegmental neuromuscular onset succession has to spread successively from the rotation axis (punctum fixum) toward the body part that shall be accelerated (punctum mobile). The aim of the present study was to investigate whether this principle is, indeed, fundamental for any kind of efficient rotational accelerations in general, independent of the kind of movements, type of rotational axis, the current body position, or movement direction. Neuromuscular onset succession was captured by surface electromyography of relevant muscles of the anterior and posterior muscle chain in 16 high-level gymnasts during intentional accelerating movement phases while performing 18 different gymnastics elements (in various body positions to forward and backward, performed on high bar, parallel bars, rings and trampoline), as well as during non-sport specific pivot movements around the longitudinal axis. The succession patterns to generate the acceleration phases during these movements were described and statistically evaluated based on the onset time difference between the muscles of the corresponding muscle chain. In all the analyzed movement phases, the results clearly support the hypothesized succession pattern from punctum fixum to punctum mobile. This principle was further underlined by the finding that the succession patterns do change their direction running through the body when the rotational axis (punctum fixum) has been changed (e.g., high bar or rings [hands] vs. floor or trampoline [feet]). The findings improve our understanding of intersegmental neuromuscular coordination patterns to generate intentional movements most efficiently. This could help to develop more specific methods to facilitate such patterns in particular contexts, thus allowing for shorter motor learning procedures of context-specific key movement sequences in different disciplines of sports, as well as during non-sport specific movements.

Concepts: Muscle, Electromyography, Classical mechanics, Acceleration, Kinematics, Rotation, Euclidean vector, Specific force