Search

Many locomotor activities require muscles to actively lengthen, dissipate energy and decelerate the body. These eccentric contractions can disrupt cytoskeletal structures within myofibrils and reduce force output. We examined how architectural features of pennate muscles can provide a protective mechanism against eccentric muscle damage by limiting fascicle lengthening. It has been previously shown that the angled fibers of pennate muscles change orientation when shortening. This change in fiber orientation can amplify fascicle shortening, resulting in a velocity advantage at the level of the muscle-tendon unit (MTU) that is characterized by a gear ratio (MTU velocity/fascicle velocity). A muscle's architectural gear ratio (AGR) has been shown to vary as a function of force during shortening, while AGR during lengthening remains largely unknown. We independently measured fascicle length and MTU length in vitro in the bullfrog plantans. We characterized the muscle's force-velocity curve and AGR during both shortening and lengthening across a broad range of forces (10-190% peak isometric force). AGR was measured during the isotonic portion of each contraction, to eliminate possible contributions of series elasticity to MTU length changes. We found that gear ratio varies with force during both shortening and lengthening contractions. The highest AGR was observed during lengthening contractions, indicating that lengthening of the MTU can occur with relatively little stretch of the fascicle. As fascicle strain is considered an important determinant of muscle damage, a high gear ratio may afford pennate muscles protection against the damaging effects of active lengthening. [ABSTRACT FROM AUTHOR]

Academic peer review is widely viewed as fair, equitable, and essential to academic quality. Successfully completing the process through publication or award is widely deemed as one of the most rigorous and prestigious forms of scholarly accomplishment. Despite this sentiment the academic peer review process is not without fault. It is criticized as being slow and influenced by "elitists" and "gatekeepers" whose motivations are not always in the best interest of adding intellectual depth or seeking Truth. Intellectual depth is what makes peer review a standard of ethics in research. It is extremely important for all involved in the peer review process to be self-critical and to take intentional steps to avoid situations whereby the integrity of the peer review process can be called into question. [ABSTRACT FROM AUTHOR]

The 2010 Research Administrators Stress Perception Survey (2010 RASPerS) collected data from 1,131 research administrators on salary, years experience, educational level, Certified Research Administrator (CRA) status, and gender. Using these data, comparisons were made to show how salary levels are associated with each of these variables. Using both descriptive and inferential statistics, salary levels were examined by creating numeric values. These data show that graduate degrees, five or more years experience, and male gender are positively associated with higher research administrator salaries, while CRA credentials, associate and bachelor degrees, and two to five years work experience are not. [ABSTRACT FROM AUTHOR]

This paper expands upon the seminal work of Roberts and House, which described the first empirical study of the demographic profile of a research administrator. The original work was based upon data from the 2005 Research Administrator Survey (RAS), a regional study of research administrators in the southeastern United States. In this paper, nationwide demographic data from the 2010 Research Administrators Stress Perception Survey (RASPerS) are compared to the 2005 RAS data. These comparisons revealed that the general profile of a research administrator continues to be overwhelmingly female (80.1%), holding a higher education degree (88.7%), and aged 40-49 years (31.9%). The 2010 data showed an extremely significant difference in the modal salary level, which increased from $50,000 to $74,999 (40.0%). In 2005, the increase was from $40,000 to $50,000 (23%). Level of education was slightly higher in 2010 than in 2005, with more research administrators holding both bachelor's and master's degrees. Additional demographic and social data are described from the 2010 RASPerS. These include both work and non-work factors. These data are offered to provide information that may be useful for others with an interest in expanding the body of knowledge about the profession of research administration. [ABSTRACT FROM AUTHOR]

The force-velocity properties of skeletal muscle have an important influence on locomotor performance. All skeletal muscles produce less force the faster they shorten and typically develop maximal power at velocities of ~30% of maximum shortening velocity (Vmax). We used direct measurements of muscle mechanical function in two ankle extensor muscles of wild turkeys to test the hypothesis that during level running muscles operate at velocities that favor force rather than power. Sonomicrometer measurements of muscle length, tendon strain-gauge measurements of muscle force, and bipolar electromyographs were taken as animals ran over a range of speeds and inclines. These measurements were integrated with previously measured values of muscle Vmax for these muscles to calculate relative shortening velocity (V/Vmax). At all speeds for level running the V/Vmax values of the lateral gastrocnemius and the peroneus longus were low (<0.05), corresponding to the region of the force-velocity relationship where the muscles were capable of producing 90% of peak isometric force but only 35% of peak isotonic power. V/Vmax increased in response to the demand for mechanical power with increases in running incline and decreased to negative values to absorb energy during downhill running. Measurements of integrated electromyograph activity indicated that the volume of muscle required to produce a given force increased from level to uphill running. This observation is consistent with the idea that V/Vmax is an important determinant of locomotor cost because it affects the volume of muscle that must be recruited to support body weight. [ABSTRACT FROM AUTHOR]

Discusses two paperback books, "The Malacia Tapestry" and "The Shattered Chain," that are written with a junk-fiction formula yet have serious themes. Contends that teachers may find the books useful in motivating thoughtful nonreaders. (FL)

The purpose of this research was to determine the demographic characteristics of research administration professionals. This is the first time that empirical research characterizing the demographic profile of research administration professionals has been conducted. The population of respondents for the study included 277 research administrators based in the southeastern region of NCURA. Data were collected utilizing an Internet-based electronic survey instrument. A total of 230 usable surveys were collected (83% rate of return). The general profile of a research administrator is: female; 40-49 years of age; bachelor's degree; 6-10 years in the profession; earning between $40-50,000 annually; and came to the field by working at a university and transferring to a predominantly research administration position. [ABSTRACT FROM AUTHOR]

We investigated the mechanical function of two ankle extensor muscles, the lateral gastrocnemius (LG) and peroneus longus (PL), in wild turkeys Meleagris gallopavo during steady speed running. We hypothesized that mechanical work output of the LG and PL during running parallels the demand for mechanical work on the body. The turkeys ran on level, inclined (+6°, +12°) and declined (-6°, -12°) treadmills to change the demand for mechanical work. Simultaneous measurements of muscle length (from sonomicrometry) and muscle force (from tendon strain gauges) were used to calculate mechanical work output. During level running at a speed of 2 m s-l, the LG and PL were both active in stance but produced peak force at different times, at approximately 21% of stance duration for the LG and 70% for the PL. The LG and PL also had different length patterns in stance during level running. The LG underwent little shortening during force production, resulting in negligible net positive work (2.0&plumsn;0.8 J kg-l). By contrast, the PL produced force across a stretch-shorten cycle in stance and did significant net positive work (4.7±1.6 J kg-l). Work outputs for both the LG and PL were directly proportional to running slope. When we increased the demand for net positive work by running the turkeys on an incline, the LG and PL increased stance net positive work output in direct proportion to slope (P<0.05). Stance net positive work output increased to 7.0±l.3 J kg-l for the LG and 8.1±2.9 J kg-l for the PL on the steepest incline. Increases in stance net positive work for the LG and PL were associated with increases in net shortening strain and average shortening velocity, but average force in stance remained constant. The LG and PL muscles were also effective energy absorbers during decline running, when there is demand for net negative work on the body. During decline running at 2 m s-l on the steepest slope, the LG absorbed 4.6±2.2 J kg-l of net work in stance and the PL absorbed 2.4±0.9 J kg-l of net work. Shifts in muscle mechanical function from energy production during incline running to energy absorption during decline running were observed over a range of running speeds from 1-3 m s-l for both the LG and PL. Two fundamentally different mechanisms for changing work output were apparent in the mechanical behavior of the LG and PL. The LG simply altered its length pattern; it actively shortened during incline running to produce mechanical energy and actively lengthened during decline running to absorb mechanical energy. The PL changed mechanical function by altering its length pattern and by shifting the timing of force production across its stretch-shorten cycle. During incline running, the PL produced force during late stance shortening for positive work, but during decline running, the timing of force production shifted into early stance, to align with lengthening for negative work. In addition, during decline running, the PL greatly reduced or eliminated late stance shortening, thus reducing the potential for positive work. Our results show that the changing demands for whole body work during steady speed running are met, at least in part, by an ability of single muscles to shift mechanical function from net energy production to net energy absorption. [ABSTRACT FROM AUTHOR]

PURPOSE: Immune checkpoint inhibitors (ICIs) are now first-line therapy for most patients with recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC), and cetuximab is most often used as subsequent therapy. However, data describing cetuximab efficacy in the post-ICI setting are limited. METHODS: We performed a single-institution retrospective analysis of patients with R/M HNSCC treated with cetuximab, either as monotherapy or in combination with chemotherapy, after receiving an ICI. We extracted objective response rate (ORR), duration of treatment (DOT), and overall survival (OS) and compared them on the basis of patient characteristics. Multivariable models assessed associations between patient and tumor characteristics and outcomes. RESULTS: We identified 70 patients treated with cetuximab after an ICI. The mean age was 67.6 years, with 60% having virus-associated HNSCC. Overall, the ORR was 21.4%, the median DOT was 1.9 months, and the median OS was 6.3 months. Patients receiving cetuximab with chemotherapy had a higher ORR (27.7% v 8.7%) and longer median DOT but similar OS compared with monotherapy. Virus-independent HNSCC had higher ORR (28.6% v 10.7%), longer DOT (3.3 v 1.2 months; hazard ratio [HR], 0.47 [95% CI, 0.25 to 0.90]), and longer OS (8.1 v 4.6 months; HR, 0.40 [95% CI, 0.19 to 0.83]). In multivariable models, virus-independent disease and negative smoking history were associated with improved OS. Concurrent chemotherapy, age, and sex were not associated with differences in OS. When assessing genomic data, TP53 mutations were associated with improved DOT (HR, 0.33 [95% CI, 0.15 to 0.70]) and OS (HR, 0.38 [95% CI, 0.17 to 0.86]). CONCLUSION: Cetuximab-based therapy shows limited efficacy in R/M HNSCC post-ICI, although outcomes were better in virus-independent HNSCC and nonsmokers. The findings may improve prognostication and patient selection for cetuximab after ICI in R/M HNSCC. [ABSTRACT FROM AUTHOR]

Focuses on a study which compared small dogs with bipedal runners, turkeys, of the same weight regarding their limb design and running mechanics. Information on the muscle force and length measurements; Details on the study; Methods and materials used in the study, including the calculation of composite muscle variables; Results of the study.

Part I. Focuses on a study which tested the link between running mechanics and energetics to see if it can be applicable to running bipeds, with reference to birds. Details on the energy consumption and cost coefficient; Methods and materials used in the study; Results of the study; Statistical information on the mean and range of step lengths, cost of transport and coefficient; Discussion on the study.

Studies the maximal flow of carbohydrates and lipids through the pathways supplying the mitochondria in a working muscle. Use of maximal flow as a parameter to test the structural capacities of symmorphosis; Comparison of oxygen and carbon dioxide exchange rates of dogs and goats; Pattern of fuel selection as a function of exercise intensity.

Suboptimal breastfeeding is a major cause of infant morbidity and mortality across the world. Inconsistent data has hampered quantification of this practice, however, limiting breastfeeding promotion efforts. As part of a clinical trial in Dhaka, Bangladesh, data was collected on breastfeeding patterns among 125 infants. Infants were ages 4 to 12 weeks (mean = 8.05, SD = 2.13) at the time of enrollment, and breastfeeding data were collected at 24 study visits during a twelve-week period. Breastfeeding status was assessed using the WHO-recommended “current status” (24-h recall) method. These data were used to calculate two measures: a longitudinal estimate of exclusive breastfeeding since birth and a simulated cross-sectional prevalence to approximate common data collection methods. Infants were then ranked based on their breastfeeding status at all study visits and grouped into quartiles and compared using hospitalization data recorded for all infants as part of the original study. These data showed large differences in estimates of exclusive breastfeeding behaviors when assessed longitudinally (8.8% exclusive breastfeeding) vs. calculating a cross-sectional prevalence (56.2% exclusive breastfeeding). Additionally, when infants were grouped by quartile of breastfeeding behavior and matched with hospitalization records, it was found that infants in the lowest quartile of breastfeeding behaviors were significantly more likely to be hospitalized than infants in the highest quartile. These results provide further evidence that current breastfeeding epidemiology studies may overestimate rates of exclusive breastfeeding. They also provide further evidence to support the significant infant health benefits from breastfeeding promotion. Trial registration: ClinicalTrials.gov NCT01899378. Registered July 10, 2013. [ABSTRACT FROM AUTHOR]

The gravitational acceleration of antimatter, g ¯ , has yet to be directly measured; an unexpected outcome of its measurement could change our understanding of gravity, the universe, and the possibility of a fifth force. Three avenues are apparent for such a measurement: antihydrogen, positronium, and muonium, the last requiring a precision atom interferometer and novel muonium beam under development. The interferometer and its few-picometer alignment and calibration systems appear feasible. With 100 nm grating pitch, measurements of g ¯ to 10%, 1%, or better can be envisioned. These could constitute the first gravitational measurements of leptonic matter, of 2nd-generation matter, and possibly, of antimatter. [ABSTRACT FROM AUTHOR]

Tendon springs influence locomotor movements in many terrestrial animals, but their roles in locomotion through fluids as well as in small-bodied mammals are less clear. We measured muscle, tendon and joint mechanics in an elbow extensor of a small fruit bat during ascending flight. At the end of downstroke, the tendon was stretched by elbow flexion as the wing was folded. At the end of upstroke, elastic energy was recovered via tendon recoil and extended the elbow, contributing to unfurling the wing for downstroke. Compared with a hypothetical 'string-like' system lacking series elastic compliance, the tendon spring conferred a 22.5% decrease in muscle fascicle strain magnitude. Our findings demonstrate tendon elastic action in a small flying mammal and expand our understanding of the occurrence and action of series elastic actuator mechanisms in fluid-based locomotion. [ABSTRACT FROM AUTHOR]

During downhill running, manoeuvring, negotiation of obstacles and landings from a jump, mechanical energy is dissipated via active lengthening of limb muscles. Tendon compliance provides a ‘shock-absorber’ mechanism that rapidly absorbs mechanical energy and releases it more slowly as the recoil of the tendon does work to stretch muscle fascicles. By lowering the rate of muscular energy dissipation, tendon compliance likely reduces the risk of muscle injury that can result from rapid and forceful muscle lengthening. Here, we examine how muscle–tendon mechanics are modulated in response to changes in demand for energy dissipation. We measured lateral gastrocnemius (LG) muscle activity, force and fascicle length, as well as leg joint kinematics and ground-reaction force, as turkeys performed drop-landings from three heights (0.5–1.5 m centre-of-mass elevation). Negative work by the LG muscle–tendon unit during landing increased with drop height, mainly owing to greater muscle recruitment and force as drop height increased. Although muscle strain did not increase with landing height, ankle flexion increased owing to increased tendon strain at higher muscle forces. Measurements of the length–tension relationship of the muscle indicated that the muscle reached peak force at shorter and likely safer operating lengths as drop height increased. Our results indicate that tendon compliance is important to the modulation of energy dissipation by active muscle with changes in demand and may provide a mechanism for rapid adjustment of function during deceleration tasks of unpredictable intensity. [ABSTRACT FROM AUTHOR]

In skeletal muscle, interactions between contractile and connective tissue elements at multiple scales result in emergent properties that determine mechanical performance. One of these phenomena is architectural gearing, which is quantified as the ratio of muscle velocity to muscle fiber velocity. Many pennate muscles operate with a gear ratio greater than one because muscles shorten through a combination of muscle fiber shortening and fiber rotation. Within a muscle, gearing is variable across contractions. During low force contractions, muscles operate at high gear while muscles operate at low gear during high force contractions. This variable gearing has a significant impact on muscle performance as muscle architectural changes favor muscle speed during fast contractions and muscle force during slow, high force contractions. We hypothesize that gearing in any given contraction is determined by the dynamic interaction of fiber-generated forces, fluid force transmission, and the elastic behavior of intramuscular connective tissues. Because muscle is isovolumetric, muscle fibers must bulge radially when they shorten. Radial bulging and fiber-generated forces off-axis from the muscle line of action exert forces that load connective tissues that ensheath fibers, fascicles, and the whole muscle. The way in which fluid pressures and fiber forces interact to load connective tissues in three-dimensions remains poorly understood because of the complex and multiscale nature of these interactions. Here we review evidence for variable gearing in pennate muscles, present a conceptual model that describes the fundamental interactions that determine gearing, and discuss where gaps remain in our understanding of the determinants and consequences of muscle shape change and variable gearing. [ABSTRACT FROM AUTHOR]