Joint-level coordination patterns for split-belt walking across different speed ratios.

Locomotion is a highly flexible process, requiring rapid changes to gait due to changes in the environment or goals. Here, we used a split-belt treadmill to examine how the central nervous system coordinates a novel gait pattern. Existing research has focused on summary measures, most often step lengths, when describing changes induced while walking on the split-belt treadmill and during subsequent aftereffects.

A proposed standard for quantifying 3-D hindlimb joint poses in living and extinct archosaurs.

The last common ancestor of birds and crocodylians plus all of its descendants (clade Archosauria) dominated terrestrial Mesozoic ecosystems, giving rise to disparate body plans, sizes, and modes of locomotion. As in the fields of vertebrate morphology and paleontology more generally, studies of archosaur skeletal structure have come to depend on tools for acquiring, measuring, and exploring three-dimensional (3-D) digital models. Such models, in turn, form the basis for many analyses of musculoskeletal function.

A new role for joint mobility in reconstructing vertebrate locomotor evolution.

Reconstructions of movement in extinct animals are critical to our understanding of major transformations in vertebrate locomotor evolution. Estimates of joint range of motion (ROM) have long been used to exclude anatomically impossible joint poses from hypothesized gait cycles. Here we demonstrate how comparative ROM data can be harnessed in a different way to better constrain locomotor reconstructions.

Gearing effects of the patella (knee extensor muscle sesamoid) of the helmeted guineafowl during terrestrial locomotion.

Human patellae (kneecaps) are thought to act as gears, altering the mechanical advantage of knee extensor muscles during running. Similar sesamoids have evolved in the knee extensor tendon independently in birds, but it is unknown if these also affect the mechanical advantage of knee extensors. Here, we examine the mechanics of the patellofemoral joint in the helmeted guineafowl using a method based on muscle and tendon moment arms taken about the patella's rotation centre around the distal femur.

3-D range of motion envelopes reveal interacting degrees of freedom in avian hind limb joints.

Measuring range of motion (ROM) is a valuable technique that can link bone morphology to joint function in both extant and extinct taxa. ROM results are commonly presented as tables or graphs of maxima and minima for each rotational degree of freedom. We investigate the interactions among three degrees of freedom using X-ray reconstruction of moving morphology (XROMM) to measure ROM of the main hind limb joints of Helmeted Guineafowl (Numida meleagris).

Experimental determination of three-dimensional cervical joint mobility in the avian neck.

Background: Birds have highly mobile necks, but neither the details of how they realize complex poses nor the evolution of this complex musculoskeletal system is well-understood. Most previous work on avian neck function has focused on dorsoventral flexion, with few studies quantifying lateroflexion or axial rotation. Such data are critical for understanding joint function, as musculoskeletal movements incorporate motion around multiple degrees of freedom simultaneously.

Guineafowl with a twist: asymmetric limb control in steady bipedal locomotion.

In avian bipeds performing steady locomotion, right and left limbs are typically assumed to act out of phase, but with little kinematic disparity. However, outwardly appearing steadiness may harbor previously unrecognized asymmetries. Here, we present marker-based XROMM data showing that guineafowl on a treadmill routinely yaw away from their direction of travel using asymmetrical limb kinematics.

Long-axis rotation: a missing degree of freedom in avian bipedal locomotion.

Ground-dwelling birds are typically characterized as erect bipeds having hind limbs that operate parasagittally. Consequently, most previous research has emphasized flexion/extension angles and moments as calculated from a lateral perspective. Three-dimensional (3D) motion analyses have documented non-planar limb movements, but the skeletal kinematics underlying changes in foot orientation and transverse position remain unclear.

The predatory ecology of Deinonychus and the origin of flapping in birds.

Most non-avian theropod dinosaurs are characterized by fearsome serrated teeth and sharp recurved claws. Interpretation of theropod predatory ecology is typically based on functional morphological analysis of these and other physical features. The notorious hypertrophied 'killing claw' on pedal digit (D) II of the maniraptoran theropod Deinonychus (Paraves: Dromaeosauridae) is hypothesized to have been a predatory adaptation for slashing or climbing, leading to the suggestion that Deinonychus and other dromaeosaurids were cursorial predators specialized for actively attacking and killing prey several times larger than themselves.

Using population segmentation to provide better health care for all: the "Bridges to Health" model.

The model discussed in this article divides the population into eight groups: people in good health, in maternal/infant situations, with an acute illness, with stable chronic conditions, with a serious but stable disability, with failing health near death, with advanced organ system failure, and with long-term frailty. Each group has its own definitions of optimal health and its own priorities among services. Interpreting these population-focused priorities in the context of the Institute of Medicine's six goals for quality yields a framework that could shape planning for resources, care arrangements, and service delivery, thus ensuring that each person's health needs can be met effectively and efficiently.

Assessment of the Medicare quality improvement organization program.

Background: Studies have shown improvement in quality of health care in the United States. However, the factors responsible for this improvement are largely unknown.

Objective: To evaluate the effect of the Medicare Quality Improvement Organization (QIO) Program in 4 clinical settings by using performance data for 41 quality measures during the 7th Scope of Work.

Pancrustacean phylogeny: hexapods are terrestrial crustaceans and maxillopods are not monophyletic.

Recent molecular analyses indicate that crustaceans and hexapods form a clade (Pancrustacea or Tetraconata), but relationships among its constituent lineages, including monophyly of crustaceans, are controversial. Our phylogenetic analysis of three protein-coding nuclear genes from 62 arthropods and lobopods (Onychophora and Tardigrada) demonstrates that Hexapoda is most closely related to the crustaceans Branchiopoda (fairy shrimp, water fleas, etc.) and Cephalocarida + Remipedia, thereby making hexapods terrestrial crustaceans and the traditionally defined Crustacea paraphyletic.

Fertilisation involving ageing gametes, major birth defects, and Down's syndrome.

For many years, ageing of gametes as a result of prolonged retention in the female reproductive tract before fertilisation has been circumstantially associated with major birth defects. To assess this association, we studied pregnant women who had recorded the timing, with regard to presumed ovulation, of the coital event leading to conception. We found major anomalies in 11 (2.

Does ovulation induction affect the pregnancy rate after laparoscopic treatment of endometriosis?

Objective: To determine the effectiveness of ovulation induction after laparoscopic treatment of endometriosis in an infertile population.

Design: An observational prospective study in which infertility cases were treated with laparoscopic surgery was followed up (mean 11 months), either by treatment (ovulation induction) or no further treatment (expectant management) and the outcomes recorded. In both groups pregnancies were compared by Cox's regression survival model.

Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning.

This was a multicentred, prospective study of pregnancies among women using natural family planning. The women maintained natural family planning charts of the conception cycle, recording acts of intercourse and signs of ovulation (cervical mucus changes, including peak day and basal body temperature). Charts were used to assess the most probable day of insemination relative to the day of ovulation and length of the follicular phase of the cycle.

Pregnancy complications in natural family planning users.

A multicenter cohort study was designed to assess pregnancy outcome among natural family planning (NFP) users, and provide the opportunity to address complications in NFP users by planning status and by timing of conception with respect to day of ovulation. There were 877 singleton births in this sample. Complications evaluated were abnormal vaginal bleeding, urinary tract infection, vaginal infection, hypertension of pregnancy, proteinuria, glycosuria, and anemia.

Effects of timing of conception on birth weight and preterm delivery of natural family planning users.

Objective: Various birth defects and untoward perinatal outcomes have been claimed to be associated with pregnancies conceived by gametes aged in vivo before fertilization. Thus, these outcomes were systematically assessed in pregnancies occurring in natural family planning (NFP) users. Our international multicenter cohort study of NFP pregnancies (n = 877) is by far the largest systematic study designed to assess pregnancy outcome and is of sufficient power to allow us to address the concern of low birth weight (< 2500 g) and preterm delivery (< 37 weeks gestation).

Pregnancy outcome in natural family planning users: cohort and case-control studies evaluating safety.

Conceptions involving aging gametes are of relevance to natural family planning (NFP) because women using NFP to avoid pregnancy abstain from intercourse during the fertile time of the cycle. To help verify the safety of pregnancies occurring among NFP practitioners, our group has, since 1986, conducted a large cohort study involving six experienced NFP centers. Timing of conception was determined from NFP charts, in which women recorded days on which intercourse occurred.

Adverse outcomes of planned and unplanned pregnancies among users of natural family planning: a prospective study.

Objectives: The purpose of this study was to determine prospectively whether unplanned pregnancies are associated with adverse pregnancy outcomes among users of natural family planning.

Methods: Women who became pregnant while using natural family planning were identified in five centers worldwide: there were 373 unplanned and 367 planned pregnancies in this cohort. The subjects were followed up at 16 and 32 weeks' gestation and after delivery.

Further evidence that infection is an infrequent cause of first trimester spontaneous abortion.

A previous cohort study found no clinical evidence that infection occurred more often in subjects experiencing pregnancy loss compared with those experiencing successful pregnancy [Simpson et al. (1996) Hum. Reprod.

Calendar rhythm efficacy: a review.

Objective: To estimate the unplanned pregnancy rate of calendar rhythm.

Design: Meta-analysis of eight studies of calendar rhythm published between 1940 and 1989.

Results: There exist few studies of the calendar rhythm method.

Timing of conception and the risk of spontaneous abortion among pregnancies occurring during the use of natural family planning.

Objective: Our purpose was to ascertain the effects of timing of conception on the risk of spontaneous abortion.

Study Design: To assess these effects, women who conceived while using natural family planning were identified in five centers worldwide between 1987 and 1993. Timing of conception was determined from 868 natural family planning charts that recorded day of intercourse and indices of ovulation (cervical mucus peak obtained according to the ovulation method and/or basal body temperature).

Roman Catholic Church-sponsored natural family planning services in the United States.

Objectives: Our objective was to determine the level and quality of natural family planning service provided by Roman Catholic Diocese-related programs in the United States.

Study Design: Programs volunteered quarterly data for five years, using least squares regression we estimated service levels for programs never reporting.

Results: From 1988 to 1992, 78 dioceses ever reported and 96 never reported.