SciCombinator

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

Concept: Reach

34

To our knowledge, ours is the first study to report on Facebook advertising as an exclusive mechanism for recruiting women ages 35-49 years residing in the USA into a health-related research study. We directed our survey to women ages 35-49 years who resided in the USA exclusively using three Facebook advertisements. Women were then redirected to our survey site. There were 20,568,960 women on Facebook that met the eligibility criteria. The three ads resulted in 899,998 impressions with a reach of 374,225 women. Of the women reached, 280 women (0.075 %) clicked the ad. Of the women who clicked the ad, nine women (3.2 %) proceeded past the introductory page. Social networking, and in particular Facebook, is an innovative venue for recruiting participants for research studies. Challenges include developing an ad to foster interest without biasing the sample, and motivating women who click the ad to complete the survey. There is still much to learn about this potential method of recruitment.

Concepts: United States, Advertising, Reach, Recruitment, MySpace, Frank Lloyd Wright, Facebook, Click

15

When deciding between alternative options, a rational agent chooses on the basis of the desirability of each outcome, including associated costs. As different options typically result in different actions, the effort associated with each action is an essential cost parameter. How do humans discount physical effort when deciding between movements? We used an action-selection task to characterize how subjective effort depends on the parameters of arm transport movements and controlled for potential confounding factors such as delay discounting and performance. First, by repeatedly asking subjects to choose between 2 arm movements of different amplitudes or durations, performed against different levels of force, we identified parameter combinations that subjects experienced as identical in effort (isoeffort curves). Movements with a long duration were judged more effortful than short-duration movements against the same force, while movement amplitudes did not influence effort. Biomechanics of the movements also affected effort, as movements towards the body midline were preferred to movements away from it. Second, by introducing movement repetitions, we further determined that the cost function for choosing between effortful movements had a quadratic relationship with force, while choices were made on the basis of the logarithm of these costs. Our results show that effort-based action selection during reaching cannot easily be explained by metabolic costs. Instead, force-loaded reaches, a widely occurring natural behavior, imposed an effort cost for decision making similar to cost functions in motor control. Our results thereby support the idea that motor control and economic choice are governed by partly overlapping optimization principles.

Concepts: Economics, Decision theory, Motor control, Decision making software, Choice, Reach, Marginal cost, Choice architecture

13

High-power lasers in the relativistic intensity regime with multi-picosecond pulse durations are available in many laboratories around the world. Laser pulses at these intensities reach giga-bar level radiation pressures, which can push the plasma critical surface where laser light is reflected. This process is referred to as the laser hole boring (HB), which is critical for plasma heating, hence essential for laser-based applications. Here we derive the limit density for HB, which is the maximum plasma density the laser can reach, as a function of laser intensity. The time scale for when the laser pulse reaches the limit density is also derived. These theories are confirmed by a series of particle-in-cell simulations. After reaching the limit density, the plasma starts to blowout back toward the laser, and is accompanied by copious superthermal electrons; therefore, the electron energy can be determined by varying the laser pulse length.

Concepts: Quantum mechanics, Fundamental physics concepts, Light, Laser, Nuclear fusion, Plasma, Reach, Laser beam profiler

12

Artificial skyglow is constantly growing on a global scale, with potential ecological consequences ranging up to affecting biodiversity. To understand these consequences, worldwide mapping of skyglow for all weather conditions is urgently required. In particular, the amplification of skyglow by clouds needs to be studied, as clouds can extend the reach of skyglow into remote areas not affected by light pollution on clear nights. Here we use commercial digital single lens reflex cameras with fisheye lenses for all-sky photometry. We track the reach of skyglow from a peri-urban into a remote area on a clear and a partly cloudy night by performing transects from the Spanish town of Balaguer towards Montsec Astronomical Park. From one single all-sky image, we extract zenith luminance, horizontal and scalar illuminance. While zenith luminance reaches near-natural levels at 5 km distance from the town on the clear night, similar levels are only reached at 27 km on the partly cloudy night. Our results show the dramatic increase of the reach of skyglow even for moderate cloud coverage at this site. The powerful and easy-to-use method promises to be widely applicable for studies of ecological light pollution on a global scale also by non-specialists in photometry.

Concepts: Light pollution, Reach, Camera, Digital single-lens reflex camera, Single-lens reflex camera, Cloud, Twin-lens reflex camera

5

This manuscript, developed by a group of leading chronic pain researchers and clinicians from around the world, aims to address the state of knowledge about fibromyalgia and identify ongoing challenges in the field of fibromyalgia and other chronic pain syndromes that may be characterized by pain centralization/amplification/hypersensitivity. There have been many exciting developments in research studies of the pathophysiology and treatment of fibromyalgia and related syndromes that have the potential to improve the recognition and management of patients with fibromyalgia and other conditions with fibromyalgia-like pain. However, much of the new information has not reached all clinicians, especially primary care clinicians, who have the greatest potential to use this new knowledge to positively impact their patients' lives. Furthermore, there are persistent misconceptions about fibromyalgia and a lack of consensus regarding the diagnosis and treatment of fibromyalgia. This paper presents a framework for future global efforts to improve the understanding and treatment of fibromyalgia and other associated chronic pain syndromes, disseminate research findings, identify ways to enhance advocacy for these patients, and improve global efforts to collaborate and reach consensus about key issues related to fibromyalgia and chronic pain in general.

Concepts: Present, Hospital, Research, Pain, Fibromyalgia, Chronic pain, Myofascial pain syndrome, Reach

4

Linguistic communication builds on prelinguistic communicative gestures, but the ontogenetic origins and complexities of these prelinguistic gestures are not well known. The current study tested whether 8-month-olds, who do not yet point communicatively, use instrumental actions for communicative purposes. In two experiments, infants reached for objects when another person was present and when no one else was present; the distance to the objects was varied. When alone, the infants reached for objects within their action boundaries and refrained from reaching for objects out of their action boundaries; thus, they knew about their individual action efficiency. However, when a parent (Experiment 1) or a less familiar person (Experiment 2) sat next to them, the infants selectively increased their reaching for out-of-reach objects. The findings reveal that before they communicate explicitly through pointing gestures, infants use instrumental actions with the apparent expectation that a partner will adopt and complete their goals.

Concepts: Causality, Communication, Reach

4

Efforts to end preventable newborn deaths will fail if the poor are not reached with effective interventions. To understand what works to reach vulnerable groups, we describe and explain the uptake of a highly effective community-based newborn health intervention across social strata in Asia and Africa.

Concepts: Reach

4

Moving is thought to take separate preparation and execution steps. During preparation, neural activity in primary motor and dorsal premotor cortices achieves a state specific to an upcoming action but movements are not performed until the execution phase. We investigated whether this preparatory state (more precisely, prepare-and-hold state) is required for movement execution using two complementary experiments. We compared monkeys' neural activity during delayed and nondelayed reaches and in a delayed reaching task in which the target switched locations on a small percentage of trials. Neural population activity bypassed the prepare-and-hold state both in the absence of a delay and if the wrong reach was prepared. However, the initial neural response to the target was similar across behavioral conditions. This suggests that the prepare-and-hold state can be bypassed if needed, but there is a short-latency preparatory step that is performed prior to movement even without a delay.

Concepts: Psychology, Reach

3

The control of targeted reaching is thought to be shaped by distinct subtypes of local GABAergic inhibitory neurons in primary forelimb motor cortex (M1). However, little is known about their action potential firing dynamics during reaching. To address this, we recorded the activity of parvalbumin-expressing (PV+) GABAergic neurons identified from a larger population of fast-spiking units and putative excitatory regular-spiking units in layer 5 of the mouse forelimb M1 during an M1-dependent, sensory-triggered reaching task. PV+ neurons showed short latency responses to the acoustic cue and vibrotactile trigger stimulus and an increase in firing at reaching onset that scaled with the amplitude of reaching. Unexpectedly, PV+ neurons fired before regular-spiking units at reach onset and showed high overall firing rates during both sensory-triggered and spontaneous reaches. Our data suggest that increasing M1 PV+ neuron firing rates may play a role in the initiation of voluntary reaching.

Concepts: Neuron, Action potential, Cerebral cortex, Cerebrum, Neurotransmitter, Membrane potential, Pyramidal cell, Reach

3

Every movement we make represents one of many possible actions. In reaching tasks with multiple targets, dorsal premotor cortex (PMd) appears to represent all possible actions simultaneously. However, in many situations we are not presented with explicit choices. Instead, we must estimate the best action based on noisy information and execute it while still uncertain of our choice. Here we asked how both primary motor cortex (M1) and PMd represented reach direction during a task in which a monkey made reaches based on noisy, uncertain target information. We found that with increased uncertainty, neurons in PMd actually enhanced their representation of unlikely movements throughout both planning and execution. The magnitude of this effect was highly variable across sessions, and was correlated with a measure of the monkeys' behavioral uncertainty. These effects were not present in M1. Our findings suggest that PMd represents and maintains a full distribution of potentially correct actions.

Concepts: Brain, Cerebral cortex, Cerebrum, Premotor cortex, Motor cortex, Monkey, Reach, Brodmann area 6