If Words Could Kill: Can the Government Regulate Any Online Speech?

From the inception of American jurisprudence, an individual’s right to freedom of speech and expression guaranteed by the First Amendment to the United States Constitution has been given some of the strongest protection available. The most celebrated legal minds in American history have consistently advocated the necessity of an open and honest exchange of ideas as fundamental to democratic society, even when the ideas expressed may be unpopular or of little value. Nonetheless, it is equally well-established that not all speech is protected, particularly where the speech in question poses a threat to public order. Although First Amendment law continues to evolve, the media available to Americans wishing to express their ideas seem to be evolving exponentially faster, particularly in the forum provided by the Internet. Indeed, the vast expansion and availability of Internet media seem to continually outstrip the much more gradual evolution of the law, not only in the United States but worldwide

A new look at the Dynamic Similarity Hypothesis: the importance of swing phase

Summary The Dynamic Similarity Hypothesis (DSH) suggests that when animals of different size walk at similar Froude numbers (equal ratios of inertial and gravitational forces) they will use similar size-corrected gaits. This application of similarity theory to animal biomechanics has contributed to fundamental insights in the mechanics and evolution of a diverse set of locomotor systems. However, despite its popularity, many mammals fail to walk with dynamically similar stride lengths, a key element of gait that determines spontaneous speed and energy costs. Here, we show that the applicability of the DSH is dependent on the inertial forces examined. In general, the inertial forces are thought to be the centripetal force of the inverted pendulum model of stance phase, determined by the length of the limb. If instead we model inertial forces as the centripetal force of the limb acting as a suspended pendulum during swing phase (determined by limb center of mass position), the DSH for stride length variation is fully supported. Thus, the DSH shows that inter-specific differences in spatial kinematics are tied to the evolution of limb mass distribution patterns. Selection may act on morphology to produce a given stride length, or alternatively, stride length may be a “spandrel” of selection acting on limb mass distribution

Metabolic acceleration and the evolution of human brain size and life history.

Humans are distinguished from the other living apes in having larger brains and an unusual life history that combines high reproductive output with slow childhood growth and exceptional longevity. This suite of derived traits suggests major changes in energy expenditure and allocation in the human lineage, but direct measures of human and ape metabolism are needed to compare evolved energy strategies among hominoids. Here we used doubly labelled water measurements of total energy expenditure (TEE; kcal day(-1)) in humans, chimpanzees, bonobos, gorillas and orangutans to test the hypothesis that the human lineage has experienced an acceleration in metabolic rate, providing energy for larger brains and faster reproduction without sacrificing maintenance and longevity. In multivariate regressions including body size and physical activity, human TEE exceeded that of chimpanzees and bonobos, gorillas and orangutans by approximately 400, 635 and 820 kcal day(-1), respectively, readily accommodating the cost of humans' greater brain size and reproductive output. Much of the increase in TEE is attributable to humans' greater basal metabolic rate (kcal day(-1)), indicating increased organ metabolic activity. Humans also had the greatest body fat percentage. An increased metabolic rate, along with changes in energy allocation, was crucial in the evolution of human brain size and life history

Trabecular Bone Orientation in Flexed Versus Extended Postures in Guinea Fowl: A Test of Wolff’s Law

Although bipedal locomotion is a hominin synapomorphy, disagreements persist about whether early hominin bipeds were capable of fully extended limb posture, or used a bent-knee, bent-hip gait. Several recent studies have used the orientation of trabecular bone in limb joints to infer posteral differences during bipedal locomotion between early bipeds and later Homo. There analyses depend on the assumption that the orientation of the trabeculae in joint corresponds to the orientation of compressive forces that are transmitted through the joints. However, the hypothesis that trabecular struts will differ in orientation because of differences in the orientation of loads they experience during growth have not been tested. This study experimentally tests the hypothesis that there is a quantifiable relationship between the orientations of trabeculae and joint posture. The experiment included 16 guinea fowl (Numida melegris): 6 extended-posture runners, 6 flexed-posture runners, and 4 sedentary controls. The exercised animals ran 6 days per week at 1.9 mph for 15 minutes, on either a flat treadmill or a treadmill inclined to 20°. Kinematic and ground reaction force data collected as the birds moved on horizontal and inclined substrates confirm that the degree of flexion at the knee at toe-off is 10° greater when moving up inclines relative to level running. Micro-CT scans were analyzed using image analysis software to relate this difference to trabecular and subchondral bone morphology within the distal femoral epiphysis, including subchondral bone thickness, and trabecular orientation, number, thickness, volume, and connectivity.AnthropologyHuman Evolutionary Biolog

Measuring the Energy of Ventilation and Circulation during Human Walking using Induced Hypoxia

Energy expenditure (EE) during walking includes energy costs to move and support the body and for respiration and circulation. We measured EE during walking under three different oxygen concentrations. Eleven healthy, young, male lowlanders walked on a treadmill at seven gait speeds (0.67–1.83 m s−1) on a level gradient under normobaric normoxia (room air, 21% O2), moderate hypoxia (15% O2), and severe hypoxia (11% O2). By comparing the hypoxia-induced elevation in heart rate (HR [bpm]), ventilation (VE [L min−1]) with the change in energy expenditure (EE [W]) at each speed, we were able to determine circulatory and respiratory costs. In a multivariate model combining HR and VE, respiratory costs were 0.44 ± 0.15 W per each L min−1 increase in VE, and circulatory costs were 0.24 ± 0.05 W per each bpm increase in HR (model adjusted r2 = 0.97, p \u3c 0.001). These VE costs were substantially lower than previous studies that ignored the contribution of HR to cardiopulmonary work. Estimated HR costs were consistent with, although somewhat higher than, measures derived from catheterization studies. Cardiopulmonary costs accounted for 23% of resting EE, but less than 5% of net walking costs (i.e., with resting EE subtracted)

Health-Chair Reform: Your Chair: Comfortable but Deadly

In the 1 h before work, a person can use more than 50labor devices. At work, between logging-on to log-ging-off, a person can remain nearly continuously intheir chair. At the end of the work-day, if the home is the castle, the chair is its throne. From their throne, a person can order food, purchase a car, find a new life-partner, and play war; all this—and more—without ever getting up. With creativity, a person can eat, work, repro-duce, play, shop, and sleep without taking a step. The articles in this issue of Diabetes by Højbjerre et al. (1), Katzmarzyk (2), and Franks (3), plus a growing body of evidence suggest that chair-living is lethal. Of concern is that for most people in the developed world, chair-living is the norm. The consequences of modern chair-dependency are substantial. The data summarized by Katzmarzyk suggest that chair-dependency is linked to cardiovascular disease, metabolic sequelae, excess weight, and shorter life span

Control and Function of Arm Swing in Human Walking and Running

We investigated the control and function of arm swing in human walking and running to test the hypothesis that the arms act as passive mass dampers powered by movement of the lower body, rather than being actively driven by the shoulder muscles. We measured locomotor cost, deltoid muscle activity and kinematics in 10 healthy adult subjects while walking and running on a treadmill in three experimental conditions: control; no arms (arms folded across the chest); and arm weights (weights worn at the elbow). Decreasing and increasing the moment of inertia of the upper body in no arms and arm weights conditions, respectively, had corresponding effects on head yaw and on the phase differences between shoulder and pelvis rotation, consistent with the view of arms as mass dampers. Angular acceleration of the shoulders and arm increased with torsion of the trunk and shoulder, respectively, but angular acceleration of the shoulders was not inversely related to angular acceleration of the pelvis or arm. Restricting arm swing in no arms trials had no effect on locomotor cost. Anterior and posterior portions of the deltoid contracted simultaneously rather than firing alternately to drive the arm. These results support a passive arm swing hypothesis for upper body movement during human walking and running, in which the trunk and shoulders act primarily as elastic linkages between the pelvis, shoulder girdle and arms, the arms act as passive mass dampers which reduce torso and head rotation, and upper body movement is primarily powered by lower body movement.AnthropologyHuman Evolutionary Biolog

Metabolic hypothesis for human altriciality

The classic anthropological hypothesis known as the “obstetrical dilemma” is a well-known explanation for human altriciality, a condition that has significant implications for human social and behavioral evolution. The hypothesis holds that antagonistic selection for a large neonatal brain and a narrow, bipedal-adapted birth canal poses a problem for childbirth; the hominin “solution” is to truncate gestation, resulting in an altricial neonate. This explanation for human altriciality based on pelvic constraints persists despite data linking human life history to that of other species. Here, we present evidence that challenges the importance of pelvic morphology and mechanics in the evolution of human gestation and altriciality. Instead, our analyses suggest that limits to maternal metabolism are the primary constraints on human gestation length and fetal growth. Although pelvic remodeling and encephalization during hominin evolution contributed to the present parturitional difficulty, there is little evidence that pelvic constraints have altered the timing of birth