SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Head

405

There is growing concern around the effects of concussion and sub-concussive impacts in sport. Routine game-play in soccer involves intentional and repeated head impacts through ball heading. Although heading is frequently cited as a risk to brain health, little data exist regarding the consequences of this activity. This study aims to assess the immediate outcomes of routine football heading using direct and sensitive measures of brain function.

Concepts: Thought, Association football, Football, Head

309

 To determine whether being elected to head of government is associated with accelerated mortality by studying survival differences between people elected to office and unelected runner-up candidates who never served.

Concepts: Head, Presidential system, Head of government

33

To determine the rate and differential contribution of heading vs unintentional head impacts (e.g., head to head, goal post) to CNS symptoms in adult amateur soccer players.

Concepts: Head

25

Skeletal unloading and cephalic fluid shifts in microgravity may alter the bone microvascular flow, and may be associated with the 1-2% bone loss per month during spaceflight. The purpose of this study was to determine if lower body negative pressure (LBNP) can prevent microgravity induced alterations of tibial microvascular flow. Head down tilt (HDT) simulates the cephalad fluid shift and microvascular flow responses that may occur in microgravity. We hypothesized that LBNP prevents HDT induced increases in tibial microvascular flow. Tibial bone microvascular flow, oxygenation and calf circumference were measured during 5min sitting, 5min supine, 5min of 15o HDT, 10min 15o HDT with 25mmHg LBNP using photoplethysmography (PPG), near infrared spectroscopy (NIRS) and strain gauge plethysmography (SGP). Measurements were made simultaneously. Tibial microvascular flow increased by 36% with 5min 15o HDT (2.2±1.1V; RMANOVA p<0.0001) from supine (1.4±0.8V). After 10min of LBNP in the 15o HDT position, tibial microvascular flow returned to supine levels (1.1±0.5V; RMANOVA p<0.001). Tibial oxygenation did not change significantly during sitting, supine, HDT, or HDT with LBNP. However, calf circumference decreased with 5min 15o HDT (-0.7±0.4V; RMANOVA p<0.0001) from supine (-0.5±0.4V). However, with LBNP calf circumference returned to supine levels (-0.4±0.1V; RMANOVA p=0.002). These data establish that simulated microgravity increases tibial microvascular flow and LBNP prevents these increases. The results suggest that LBNP may provide a suitable countermeasure to normalize the bone microvascular flow during spaceflight.

Concepts: Spectroscopy, Bone, Measurement, Infrared spectroscopy, Infrared, Near infrared spectroscopy, Flow to HDL, Head

8

Myosin 5a is a dual-headed molecular motor that transports cargo along actin filaments. By following the motion of individual heads with interferometric scattering microscopy at nm spatial and ms temporal precision we found that the detached head occupies a loosely fixed position to one side of actin from which it rebinds actin in a controlled and manner while executing a step. Improving the spatial precision to the sub-nm regime provided evidence for an angstrom-level structural transition in the motor domain associated with the power stroke. Simultaneous tracking of both heads revealed that consecutive steps follow identical paths to the same side of actin in a compass-like spinning motion demonstrating a symmetrical walking pattern. These results visualize many of the critical unknown aspects of the stepping mechanism of myosin 5 including head-head coordination, the origin of lever-arm motion and the spatiotemporal dynamics of the translocating head during individual steps.

Concepts: Protein, Actin, Molecular motor, Transport, Power, Sustainable transport, Head

3

Fetal malpositions and cephalic malpresentations are a well recognized cause of failure to progress in labor. They frequently require operative delivery, and are associated with an increased probability of fetal and maternal complications. Traditional obstetrics emphasizes the role of digital examinations, but recent studies have demonstrated that this approach is inaccurate and that intrapartum ultrasound is far more precise. The objective of this review is to summarize the current body of literature and provide recommendations to identify malpositions and cephalic malpresentations with ultrasound. We propose a systematic approach consisting of a combination of transabdominal and transperineal scans and describe the findings that allow an accurate diagnosis of normal and abnormal position, flexion and synclitism of the fetal head. The management of malpositions and cephalic malpresentation is currently a matter of debate, and is individualized depending upon the general clinical picture and the expertise of the provider. Intrapartum sonography allows a precise diagnosis and therefore offers the best opportunity to design prospective studies with the aim of establishing evidence-based treatment. The article is accompanied by a video that demonstrates the sonographic technique and findings.

Concepts: Pregnancy, Childbirth, Diagnosis, Medical imaging, Obstetrics, Medical ultrasonography, Demonstration, Head

2

It has previously been shown that language production, performed simultaneously with a nonlinguistic task, involves sustained attention. Sustained attention concerns the ability to maintain alertness over time. Here, we aimed to replicate the previous finding by showing that individuals call upon sustained attention when they plan single noun phrases (e.g., “the carrot”) and perform a manual arrow categorization task. In addition, we investigated whether speakers also recruit sustained attention when they produce conjoined noun phrases (e.g., “the carrot and the bucket”) describing two pictures, that is, when both the first and second task are linguistic. We found that sustained attention correlated with the proportion of abnormally slow phrase-production responses. Individuals with poor sustained attention displayed a greater number of very slow responses than individuals with better sustained attention. Importantly, this relationship was obtained both for the production of single phrases while performing a nonlinguistic manual task, and the production of noun phrase conjunctions in referring to two spatially separated objects. Inhibition and updating abilities were also measured. These scores did not correlate with our measure of sustained attention, suggesting that sustained attention and executive control are distinct. Overall, the results suggest that planning conjoined noun phrases involves sustained attention, and that language production happens less automatically than has often been assumed.

Concepts: Grammar, Phrase, Performance, Noun, Head, Noun phrase, Phrases

2

Bird songs range in form from the simple notes of a Chipping Sparrow to the rich performance of the nightingale. Non-adjacent correlations can be found in the syntax of some birdsongs, indicating that the choice of what to sing next is determined not only by the current syllable, but also by previous syllables sung. Here we examine the song of the domesticated canary, a complex singer whose song consists of syllables, grouped into phrases that are arranged in flexible sequences. Phrases are defined by a fundamental time-scale that is independent of the underlying syllable duration. We show that the ordering of phrases is governed by long-range rules: the choice of what phrase to sing next in a given context depends on the history of the song, and for some syllables, highly specific rules produce correlations in song over timescales of up to ten seconds. The neural basis of these long-range correlations may provide insight into how complex behaviors are assembled from more elementary, stereotyped modules.

Concepts: Bird, Grammar, Phrase, Music, Syntax, Poetry, Head, Bird vocalization

1

The ability to actively follow a moving auditory target with our heads remains unexplored even though it is a common behavioral response. Previous studies of auditory motion perception have focused on the condition where the subjects are passive. The current study examined head tracking behavior to a moving auditory target along a horizontal 100° arc in the frontal hemisphere, with velocities ranging from 20 to 110°/s. By integrating high fidelity virtual auditory space with a high-speed visual presentation we compared tracking responses of auditory targets against visual-only and audio-visual “bisensory” stimuli. Three metrics were measured-onset, RMS, and gain error. The results showed that tracking accuracy (RMS error) varied linearly with target velocity, with a significantly higher rate in audition. Also, when the target moved faster than 80°/s, onset and RMS error were significantly worst in audition the other modalities while responses in the visual and bisensory conditions were statistically identical for all metrics measured. Lastly, audio-visual facilitation was not observed when tracking bisensory targets.

Concepts: Psychology, Measurement, Derivative, The Target, Behavior, Velocity, Target Corporation, Head

1

Heading impairs cognition in the short and medium-terms; however, little is known about the long-term consequences. This study aimed to investigate the hypothesis that chronic low-level head trauma is associated with persistent cognitive decline.

Concepts: Cognition, Knowledge, Football, Head