Muscle Function and Fatigability of Trunk Flexors in Males and Females

Background Optimal function of the abdominal muscles is necessary for several life functions including lifting and carrying tasks. Sex differences in strength and fatigability are established for many limb muscles and back extensor muscles, but it is unknown if sex differences exist for the abdominal muscles despite their functional importance. Methods Eighteen females (24.3 ± 4.8 years) and 15 males (24.1 ± 6.6 years) performed (1) isometric trunk flexion maximal voluntary contractions (MVCs) in a range of trunk positions to establish a torque-angle curve and (2) submaximal (50% MVC), intermittent isometric contraction (6 s on, 4 s off) until task failure to determine fatigability of the trunk flexor muscles. Dual X-ray absorptiometry quantified body fat and lean mass. Physical activity levels were quantified with a questionnaire. Torque-angle curves, electromyography (EMG), MVC torque, and torque steadiness were compared with repeated measures ANOVA with sex as a between-subjects factor. Results For the torque-angle curve, MVC torque was reduced as the trunk angle increased toward flexion (p \u3c 0.001). Males had greater MVC torque than females at the extended positions (31% difference), with no sex differences in torque in upright sitting (p \u3e 0.05). Time-to-task failure for the submaximal fatigability task in upright sitting was similar between males and females (12.4 ± 7 vs 10.5 ± 6 min). Time-to-task failure was positively associated with strength (r = 0.473, p = 0.005) and self-reported physical activity (r = 0.456, p = 0.030). Lean mass in the trunk was positively associated with trunk flexor strength (r = 0.378, p = 0.011) and self-reported physical activity (r = 0.486, p = 0.007). Finally, torque steadiness [coefficient of variation of torque (CV)] during submaximal isometric contractions decreased with contraction intensity and was similar for males and females across all intensities. Conclusions Unlike many limb muscle groups, males and females had similar fatigability and torque steadiness of the trunk flexor muscles during isometric contractions. Stronger individuals, however, exhibited less fatigability. Lower self-reported physical activity was associated with greater fatigability of trunk flexor muscles. The relationship between strength and fatigability of the trunk flexor muscles and physical activity supports the importance of abdominal muscle strengthening to offset fatigability in both males and females

The impact of functional imaging on radiation medicine

Radiation medicine has previously utilized planning methods based primarily on anatomic and volumetric imaging technologies such as CT (Computerized Tomography), ultrasound, and MRI (Magnetic Resonance Imaging). In recent years, it has become apparent that a new dimension of non-invasive imaging studies may hold great promise for expanding the utility and effectiveness of the treatment planning process. Functional imaging such as PET (Positron Emission Tomography) studies and other nuclear medicine based assays are beginning to occupy a larger place in the oncology imaging world. Unlike the previously mentioned anatomic imaging methodologies, functional imaging allows differentiation between metabolically dead and dying cells and those which are actively metabolizing. The ability of functional imaging to reproducibly select viable and active cell populations in a non-invasive manner is now undergoing validation for many types of tumor cells. Many histologic subtypes appear amenable to this approach, with impressive sensitivity and selectivity reported

Solving the Problem of Time in Mini-superspace: Measurement of Dirac Observables

One solution to the so-called problem of time is to construct certain Dirac observables, sometimes called evolving constants of motion. There has been some discussion in the literature about the interpretation of such observables, and in particular whether single Dirac observables can be measured. Here we clarify the situation by describing a class of interactions that can be said to implement measurements of such observables. Along the way, we describe a useful notion of perturbation theory for the rigging map eta of group averaging (sometimes loosely called the physical state "projector"), which maps states from the auxiliary Hilbert space to the physical Hilbert space.Comment: 12 pages, ReVTe

Fatigability of the Lumbopelvic Stabilizing Muscles in Women 8 and 26 Weeks Postpartum

Background: Pregnancy and childbirth are associated with lumbopelvic pain and instability. Fatigability of the lumbopelvic stabilizing muscles after childbirth is unknown, and no clinical tests exist to assess this important metric of muscle function. Objectives: To compare fatigability of the lumbopelvic stabilizing muscles in postpartum and nulligravid (control) women using the Active Straight Leg Raise (ASLR) Fatigue Task, and to determine whether fatigability is associated with interrecti distance (IRD), physical function, and pain/disability. Study design: A longitudinal case-control study. Methods: Twenty-nine nulligravid (25.4 +/- 9.1 years) and 31 postpartum women (31.4 +/- 5.2 years; vaginal delivery n = 18) were tested at 2 time points, 16 weeks apart (postpartum women tested at 8-10 and 24-26 weeks postpartum). Muscular function was assessed with manual muscle testing (MMT), the ASLR test, and a new ASLR Fatigue Task. Other measures included IRD, rectus abdominis thickness, physical activity, and 6-minute walk distance. Results: Postpartum women were 23% more fatigable (P = .028) and were weaker (MMT) (P \u3c .001) than controls up to 26 weeks postpartum. The ASLR Fatigue Task (time-to-failure) was associated with smaller IRD, greater rectus abdominis thickness, higher physical activity levels, greater MMT strength, and further distance walked in 6 minutes (P \u3c .05). Conclusion: Postpartum women (up to 6 months) had greater fatigability of the lumbopelvic stabilizing muscles and lower physical function than nulligravid women, suggesting core muscle function and fatigability should be assessed after pregnancy and childbirth. The ASLR Fatigue Task could be a clinically useful tool to determine fatigability of the lumbopelvic stabilizing muscles in women postpartum

Quantifying Entanglement Production of Quantum Operations

The problem of entanglement produced by an arbitrary operator is formulated and a related measure of entanglement production is introduced. This measure of entanglement production satisfies all properties natural for such a characteristic. A particular case is the entanglement produced by a density operator or a density matrix. The suggested measure is valid for operations over pure states as well as over mixed states, for equilibrium as well as nonequilibrium processes. Systems of arbitrary nature can be treated, described either by field operators, spin operators, or any other kind of operators, which is realized by constructing generalized density matrices. The interplay between entanglement production and phase transitions in statistical systems is analysed by the examples of Bose-Einstein condensation, superconducting transition, and magnetic transitions. The relation between the measure of entanglement production and order indices is analysed.Comment: 20 pages, Revte

Holographic Thought Experiments

The Hamiltonian of classical anti-de Sitter gravity is a pure boundary term on-shell. If this remains true in non-perturbative quantum gravity then i) boundary observables will evolve unitarily in time and ii) the algebra of boundary observables is the same at all times. In particular, information available at the boundary at any one time t_1 remains available at any other time t_2. Since there is also a sense in which the equations of motion propagate information into the bulk, these observations raise what may appear to be potential paradoxes concerning simultaneous (or spacelike separated) measurements of non-commuting observables, one at the asymptotic boundary and one in the interior. We argue that such potentially paradoxical settings always involve a breakdown of semi-classical gravity. In particular, we present evidence that making accurate holographic measurements over short timescales radically alters the familiar notion of causality. We also describe certain less intrinsically paradoxical settings which illustrate the above boundary unitarity and render the notion more concrete.Comment: 24 page

Methodological Issues in Evaluating Workplace Interventions to Reduce Work-related Musculoskeletal Disorders Through Mechanical Exposure Reduction

Researchers of work-related musculoskeletal disorders are increasingly asked about the evidentiary base for mechanical exposure reductions. Mixed messages can arise from the different disciplinary cultures of evidence, and these mixed messages make different sets of findings incommensurate. Interventions also operate at different levels within workplaces and result in different intensities of mechanical exposure reduction. Heterogeneity in reporting intervention processes and in measuring relevant outcomes makes the synthesis of research reports difficult. As a means of synthesizing the current understanding of measures, this paper describes a set of intervention and observation nodes for which relevant workplace indicators prior to, during, and after mechanical exposure reduction can provide useful information. On the basis of this path of impacts from exposure reduction, an approach to the evaluation of multilevel ergonomic interventions is described that can assist fellow researchers in producing evidence relevant to the challenges faced by workplace parties and policy makers

Triarchic or septarchic?—Uncovering the Triarchic Psychopathy Measure’s (TriPM) structure.

The Triarchic Psychopathy Measure (TriPM) is based on a 3-dimensional conceptual model, though few studies have directly tested a 3-factor structure. The current study used a large community sample (N = 1,064, 53% males, Mage = 34) to test the structure of the TriPM via exploratory and confirmatory factor analysis, along with 4 community replication samples from North American and Europe (Ns = 511–603, 33–49% males) and 1 European male offender sample (N = 150). Three of these samples were also used to model the correlations between relevant external correlates and the original TriPM factors versus emergent factors to examine the cost of misspecifying TriPM structure. The model analyses did not support a 3-factor model (comparative fit index = .76, root mean square error of approximation = .08), revealing a number of items with limited statistical information, but uncovered a 7-factor structure (comparative fit index = .92, root mean square error of approximation = .04). From the majority of Boldness, Meanness, and Disinhibition scale items, respectively, emerged 3 factors reflecting Positive Self-Image, Leadership, and Stress Immunity; 2 factors tapping Callousness and Enjoy Hurting; and 2 factors involving Trait Impulsivity and Overt Antisociality. Further, the Enjoy Hurting and Overt Antisociality factors were more strongly correlated with one another than with the other scales from their home domains (Callousness and Impulsivity). All 7 emergent factors were differentially associated with the external correlates, suggesting that the 3 original TriPM factors do not optimally represent the conceptual model underlying the TriPM. (PsycINFO Database Record (c) 2020 APA, all rights reserved

Subthalamic Nucleus and Sensorimotor Cortex Activity During Speech Production

The sensorimotor cortex is somatotopically organized to represent the vocal tract articulators such as lips, tongue, larynx, and jaw. How speech and articulatory features are encoded at the subcortical level, however, remains largely unknown. We analyzed LFP recordings from the subthalamic nucleus (STN) and simultaneous electrocorticography recordings from the sensorimotor cortex of 11 human subjects (1 female) with Parkinson´s disease during implantation of deep-brain stimulation (DBS) electrodes while they read aloud three-phoneme words. The initial phonemes involved either articulation primarily with the tongue (coronal consonants) or the lips (labial consonants). We observed significant increases in high-gamma (60?150 Hz) power in both the STN and the sensorimotor cortex that began before speech onset and persisted for the duration of speech articulation. As expected from previous reports, in the sensorimotor cortex, the primary articulators involved in the production of the initial consonants were topographically represented by high-gamma activity. We found that STN high-gamma activity also demonstrated specificity for the primary articulator, although no clear topography was observed. In general, subthalamic high-gamma activity varied along the ventral?dorsal trajectory of the electrodes, with greater high-gamma power recorded in the dorsal locations of the STN. Interestingly, the majority of significant articulator-discriminative activity in the STN occurred before that in sensorimotor cortex. These results demonstrate that articulator-specific speech information is contained within high-gamma activity of the STN, but with different spatial and temporal organization compared with similar information encoded in the sensorimotor cortex.Fil: Chrabaszcz, Anna. University of Pittsburgh; Estados UnidosFil: Neumann, Wolf Julian. Universität zu Berlin; AlemaniaFil: Stretcu, Otilia. University of Pittsburgh; Estados UnidosFil: Lipski, Witold J.. University of Pittsburgh; Estados UnidosFil: Dastolfo Hromack, Christina A.. University of Pittsburgh; Estados UnidosFil: Bush, Alan. University of Pittsburgh; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Wang, Dengyu. Tsinghua University; China. University of Pittsburgh; Estados UnidosFil: Crammond, Donald J.. University of Pittsburgh; Estados UnidosFil: Shaiman, Susan. University of Pittsburgh; Estados UnidosFil: Dickey, Michael W.. University of Pittsburgh; Estados UnidosFil: Holt, Lori L.. University of Pittsburgh; Estados UnidosFil: Turner, Robert S.. University of Pittsburgh; Estados UnidosFil: Fiez, Julie A.. University of Pittsburgh; Estados UnidosFil: Richardson, R. Mark. University of Pittsburgh; Estados Unido