Electromagnetic Interference in Measurements of Radial Stress During Split Hopkinson Pressure Bar Experiments.

Split Hopkinson pressure bar experiments on soils are often carried out using a rigid steel confining ring to provide plane strain conditions, and measurements of the circumferential strain in the ring can be used to infer the radial stress on the surface of the specimen. Previous experiments have shown evidence of irregular electromagnetic interference in measurements of radial stress, which obscures the signals and impedes analysis. The development of robust constitutive models for soils in blast and impact events relies on the accurate characterisation of this behaviour, and so it is necessary to isolate and remove the source of interference. This paper uses an induction coil to identify the source of the anomalous signals, which are found to be due to induced currents in the gauge lead wires from the movement of magnetised pressure bars (martensitic stainless steel, 440C). Comparative experiments on sand and rubber specimens are used to show that the deforming soil specimen does not make a significant contribution to this activity, and recommendations are made on reducing electromagnetic interference to provide reliable radial stress measurements.

Utilization of a National Registry to influence opioid prescribing behavior after hernia repair.

PURPOSE: Despite progress toward curtailing opioid prescribing, physicians are often slow to adopt new prescribing practices. Using the Abdominal Core Health Quality Collaborative (ACHQC), we aimed to demonstrate the ability of a national, disease-specific, personalized registry to impact opioid prescribing. METHODS: Using a collaborative and iterative process, a module was developed to capture surgeon opioid prescribing, patient-reported consumption, and risk factors for opioid use. Study reported according to the Standards for Quality Improvement Reporting Excellence (SQUIRE) 2.0 guidelines. RESULTS: Six months after implementation of the ACHQC opioid module, we assessed participation, prescribing and patient consumption patterns. For ventral hernia repair (VHR; n = 398), 23 surgeons reported prescribing > 20 pills (43%), 11-20 (40%), and < 10 (18%). In contrast, patients (n = 217) reported taking < 10 pills in 65% and only 20% reported taking > 15. For inguinal hernia repair (IHR; n = 443) 37 surgeons reported prescribing > 20 tablets (22%), 11-20 (32%), and < 10 (44%). Patients (n = 277) reported taking < 10 pills in 81% of cases, including 50% reporting zero, and only 13% taking > 15. We identified barriers to practice change and developed a strategy for education, provision of individualized data, and encouraging participation. Surgeon participation has since increased significantly (n = 65 for VHR; n = 53 for IHR), and analysis of the impact of this process is ongoing. CONCLUSION: Quality improvement requires physician engagement, which can be facilitated by meaningful and actionable data. The specificity of the ACHQC and the ability to provide surgeons with individualized data is a model method to incite change in physician behavior and improve patient outcomes.

Barbed sutures reduce arthrotomy closure duration compared to interrupted conventional sutures for total knee arthroplasty: a randomized controlled trial.

BACKGROUND: The broad aim of this study was to compare the safety and efficacy of using barbed sutures versus standard-of-care sutures for closure of arthrotomy during total knee arthroplasty. Specifically, we compared the duration of arthrotomy closure, the number of sutures utilized for arthrotomy closure, and 90-day outcomes, including wound-related readmission, reoperation, and complications. MATERIALS AND METHODS: A total of 60 patients undergoing primary total knee arthroplasty were enrolled in a prospective, blinded trial and randomized to receive either running closure of the arthrotomy with barbed sutures (n = 30) or interrupted closure with standard-of-care sutures (n = 30). RESULTS: Arthrotomy closure time was significantly shorter in the barbed suture group (3 min ± 2 min) versus the standard-of-care group (13 min ± 5 min, p < 0.001). The average suture utilization for arthrotomy closure was 1 suture (range 1-2) versus 3 sutures (range 2-4) in the standard-of-care group (p < 0.001). The overall number of wound-related complications in the barbed suture group was 3/30 (10%) versus 3/30 (10%) in the standard-of-care group (p = 1.00). There was one dehiscence 1/30 (3%) in the standard-of-care group versus zero in the barbed suture group (p = 1.00). The rate of superficial surgical site infection was 1/30 (3%) in barbed suture versus zero in the standard-of-care groups (p = 1.00). CONCLUSION: These results suggest barbed suture utilization may be faster and more resource-efficient than the use of standard-of-care sutures for arthrotomy closure in primary total knee arthroplasty without increased complications. CLINICALTRIALS. GOV IDENTIFIER: NCT03285529.

Primary thoracoabdominal hernias.

BACKGROUND: Primary thoracoabdominal hernias involve the triad of an intercostal hernia, abdominal wall hernia, and diaphragmatic hernia. We report a case series of this rare entity and describe the evolution and outcomes. METHODS: We completed a retrospective analysis of thoracoabdominal hernia repairs performed January 2010-April 2019 at Prisma Health-Upstate and Carolinas Medical Center. This includes all patients with spontaneous defects, excluding incisional hernias or those resulting from external trauma. RESULTS: Of 16 patients with thoracoabdominal hernias, 15 patients developed hernias after forceful coughing and one patient developed a hernia after strenuous physical activity. Seven patients required at least one additional intervention; two for recurrence; two for recurrence of original intercostal repairs done elsewhere; two for wound complications; and one had a missed abdominal wall component. CONCLUSIONS: Primary thoracoabdominal hernias require a high index of suspicion. Durable repair involves complex reconstruction of the thoracoabdominal wall including the diaphragm, intercostal space, rib fracture fixation, and mesh reinforcement of the abdominal wall with permanent fixation constructs.

Computed tomography imaging in ventral hernia repair: can we predict the need for myofascial release?

INTRODUCTION: Currently, the need for additional myofascial release (AMR) in addition to retromuscular dissection during open Rives-Stoppa hernia repair is determined intraoperatively based on the discretion of the surgeon. We developed a novel method to objectively predict the need for AMR preoperatively using computed tomography (CT)-measured rectus width to hernia width ratio (RDR). METHODS: A retrospective chart review of all patients who underwent open retro-muscular mesh repair of midline ventral hernia between August 1, 2007 and February 1, 2018, who had a preoperative CT scan within 1 year prior to their operation. The primary endpoint was the ability of the defect ratio to predict the need for AMR in pursuit of fascial closure. The secondary endpoint was the ability of Component Separation Index (CSI) to predict the need for AMR to obtain fascial closure. RESULTS: Of 342 patients, 208 repaired with rectus abdominis release alone (RM group), while 134 required AMR (RM + group). An RDR of > 1.34 on area under the curve analysis predicted the need for AMR with 77.6% accuracy. There was a linear decrease in the need for AMR with increasing RDR: RDR < 1 required AMR in 78.8% of cases, RDR 1.1-1.49 in 52%, RDR 1.5-1.99 in 32.1%, and RDR > 2 in just 10.8%. Similarly, CSI > 0.146 predicted the need for AMR with 76.3% accuracy on area under the curve analysis. CONCLUSION: The RDR is a practical and reliable tool to predict the ability to close the defect during open Rives-Stoppa ventral hernia repair without AMR. An RDR of > 2 portends fascial closure with rectus abdominis myofascial release alone in 90% of cases.

Prophylactic mesh augmentation using permanent synthetic mesh: outcomes of keyhole and Stapled Ostomy Reinforcement with Retromuscular Mesh techniques.

INTRODUCTION: Parastomal hernias (PSH) are the most common complication of stoma creation and can cause significant morbidity. We present a consecutive series of patients receiving prophylactic mesh augmentation (PMA) for prevention of PSH. METHODS: This retrospective review evaluates the efficacy and outcomes of PMA for PSH prevention, and retrospectively compares traditional keyhole PMA (tPMA) (n = 28) with a prophylactic Stapled Ostomy Reinforcement with Retromuscular Mesh technique (pSTORRM) (n = 24). RESULTS: PMA was performed in 52 cases between January 2015 and July 2018. All cases used a large-pore, non-coated, mid-weight polypropylene mesh placed in the retrorectus space. With a median follow-up of 16 mos, parastomal hernia was confirmed in 11.5% (n = 6), 5 of whom were symptomatic. patient-reported outcomes (PRO) indicated 6 additional patients with symptoms associated with PSH without clinical or radiographic confirmation. Patients had similar comorbidities and operative characteristics between tPMA and pSTORRM techniques, and no difference in a median follow-up. pSTORRM patients had fewer surgical site infections (8.3 vs 32.1%; p = 0.046) and occurrences (12.5 vs 46.4%; p = 0.015), and lower rate of PSH, though not statistically significant (4.2 vs 17.9%; p = 0.195). CONCLUSION: Permanent synthetic mesh placed as a sublay in the retromuscular space is safe and appears to decrease the risk of PSH formation after the creation of permanent stomas. A stapled technique may provide advantages over a traditional keyhole technique.

Self-consistent modeling of anisotropic interfaces and missing orientations: Derivation from phase-field crystal.

Highly anisotropic interfaces play an important role in the development of material microstructure. Using the diffusive atomistic phase-field crystal (PFC) formalism, we determine the capability of the model to quantitatively describe these interfaces. Specifically, we coarse grain the PFC model to attain both its complex amplitude formulation and its corresponding phase-field limit. Using this latter formulation, in one-dimensional calculations, we determine the surface energy and the properties of the Wulff shape. We find that the model can yield Wulff shapes with missing orientations, the transition to missing orientations, and facet formation. We show that the corresponding phase-field limit of the complex amplitude model yields a self-consistent description of highly anisotropic surface properties that are a function of the surface orientation with respect to the underlying crystal lattice. The phase-field model is also capable of describing missing orientations on equilibrium shapes of crystals and naturally includes a regularizing contribution. We demonstrate, in two dimensions, how the resultant model can be used to study growth of crystals with varying degrees of anisotropy in the phase-field limit.

Case report of carbamazepine-induced reticulocytes.

The authors present the case of a woman with bipolar disorder who developed reticulocytosis after two trials of carbamazepine. They urge that blood indices be carefully monitored whenever carbamazepine is used.

A preview of implantable cardioverter defibrillator systems in the next millennium: an integrative cardiac rhythm management approach.

The implantable cardioverter defibrillator (ICD), a primary therapeutic option for preventing sudden cardiac death, has rapidly evolved since being introduced clinically in 1980. Technologic advances in several key areas have enabled ICDs to provide more sophisticated rhythm management. Recent emphasis has been placed on dual-chamber ICDs possessing adaptive-rate pacing capabilities. Adoption of dual-chamber ICD systems has been rapid. The capabilities of future ICD systems will be governed by an integrative strategy that brings together sets of features specifically targeted at multifaceted rhythm disorders. The addition of atrial therapy will require more sophisticated rhythm discrimination algorithms. ICD technology will improve on several fronts including leads, integrated circuits, batteries, and capacitors. Additionally, state-of-the-art pacemaker technology will continue to be incorporated into ICDs. As these new ICD systems become increasingly sophisticated from an engineering viewpoint, tremendous emphasis will be placed on decreasing the complexity of programming, device interrogation, and patient monitoring during routine patient follow-up. Vast improvements in ICD programming systems may ultimately permit the 1-minute follow-up.

Future of bradyarrhythmia therapy systems: automaticity.

Since the first fixed-rate ventricular pacemaker was introduced in the late 1950s, pacing systems have evolved rapidly. Current developments focus on making devices more sophisticated and less complex--a challenging combination. Automaticity features such as beat-by-beat capture verification, sensitivity threshold adaptation, and algorithms to govern dynamically the maximum sensor rate have either recently been introduced or are likely to be introduced in the near future. Technologic advances are likely to allow meaningful improvements in current drain, battery performance, memory capacity, signal processing, telemetry, and programmer interface. Bradyarrhythmia therapy devices of the future promise to go beyond the pacemaker. Ultimately, pacing systems will become part of integrated cardiac rhythm management systems.

Hemodynamic responses during exercise at and above VO2max in swine.

Mean arterial pressure (Pa), heart rate, cardiac output (Q), and Q distribution (with radiolabeled microspheres) were measured in miniature swine as they ran at high levels on a motor-driven treadmill. Each animal ran on two occasions: once during exercise at maximal O2 uptake (VO2max) and once at an intensity estimated to require approximately 115% VO2max. The purpose was to assess these cardiovascular variables to determine whether the calculated resistance to blood flow during supramaximal exercise was different from that during maximal exercise. A total of 114 tissues/organs were dissected for blood flow analysis. Pa and Q were unaltered between the two exercise conditions. Blood flow to all but one of the 62 skeletal muscles sampled was unchanged between conditions as were the blood flows to the visceral organs and brain. The results demonstrate that vascular resistance was constant in all these tissues between maximal and supramaximal exercise intensities. Elevated blood flows were measured in 7 of the 11 coronary sites sampled. Calculated resistance to blood flow indicated that a decrease in resistance occurred in most of the samples having elevated blood flow. Because heart rate was elevated during the supramaximal exercise, the increase in blood flow was probably in response to the greater myocardial work and concomitant elevation in O2 demand. In summary, it was shown that Pa, Q, and Q distribution in most tissues remained unchanged during exercise at intensities above VO2max. Thus a precise matching occurs between the increasingly powerful vasoconstrictor drive initiated by the sympathetic nervous system and the elevated local vasodilatory drive responding to the greater O2 demand during the supramaximal exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated muscle vitamin E does not attenuate eccentric exercise-induced muscle injury.

The purpose of this study was to evaluate the effect of elevated muscle vitamin E content on skeletal muscle damage from eccentric exercise. Sixty Sprague-Dawley rats were put on a normal (40 IU vitamin E/kg food) or supplemented (10,000 IU vitamin E/kg food) diet for 5 wk. Injury in soleus muscle was determined using several criteria: reductions in maximal tetanic force and number of intact fibers per square millimeter and elevations in muscle glucose 6-phosphate dehydrogenase activity and plasma creatine kinase activity, either immediately (0 h) or 2 days (48 h) after a downhill walking protocol. Sedentary animals were also tested but did not exercise. Muscle vitamin E levels were significantly elevated (approximately 3- to 4-fold), and susceptibility of the muscles to oxidant stress was decreased, after supplementation. However, vitamin E supplementation did not attenuate injury by any of the criteria employed. Maximal tetanic force decreased approximately 20% at 0 and 48 h after exercise in both groups. The number of intact fibers per square millimeter decreased approximately 30-35% in both groups at 0 and 48 h. Glucose 6-phosphate dehydrogenase activity increased approximately 50-100% in both groups at 48 h, and plasma creatine kinase activity was elevated approximately 2- to 2.5-fold at 0 h in both groups. These findings do not support a major role for free radical damage to muscle membranes in the initiation of injury from eccentric exercise, although they do not disprove free radical involvement in the etiology.

Mechanisms of exercise-induced muscle fibre injury.

Exercise for which a skeletal muscle is not adequately conditioned results in focal sites of injury distributed within and among the fibres. Exercise with eccentric contractions is particularly damaging. The injury process can be hypothesised to occur in several stages. First, an initial phase serves to inaugurate the sequence. Hypotheses for the initial event can be categorised as either physical or metabolic in nature. We argue that the initial event is physical, that stresses imposed on sarcolemma by sarcomere length inhomogeneities occurring during eccentric contractions cause disruption of the normal permeability barrier provided by the cell membrane and basal lamina. This structural disturbance allows Ca++ to enter the fibre down its electrochemical gradient, precipitating the Ca++ overload phase. If the breaks in the sarcolemma are relatively minor, the entering Ca++ may be adequately handled by ATPase pumps that sequester and extrude Ca++ from the cytoplasm ('reversible' injury). However, if the Ca++ influx overwhelms the Ca++ pumps and free cytosolic Ca++ concentration rises, the injury becomes 'irreversible'. Elevations in intracellular Ca++ levels activate a number of Ca(++)-dependent proteolytic and phospholipolytic pathways that are indigenous to the muscle fibres, which respectively degrade structural and contractile proteins and membrane phospholipids; for instance, it has been demonstrated that elevation of intracellular Ca++ levels with Ca++ ionophores results in loss of creatine kinase activity from the fibres through activation of phospholipase A2 and subsequent production of leukotrienes. This autogenetic phase occurs prior to arrival of phagocytic cells, and continues during the inflammatory period when macrophages and other phagocytic cells are active at the damage site. The phagocytic phase is in evidence by 2 to 6 hours after the injury, and proceeds for several days. The regenerative phase then restores the muscle fibre to its normal condition. Repair of the muscle fibres appears to be complete; the fibres adapt during this process so that future bouts of exercise of similar type, intensity, and duration cause less injury to the muscle.

Red blood cell pulmonary capillary transit time during exercise in athletes.

The purpose of this study was to test the hypothesis that the exercise-induced hypoxemia observed in endurance athletes is due to a reduction in the mean red blood cell pulmonary capillary transit time consequent to a plateau in pulmonary capillary blood volume (Vc) as exercise intensity progresses from moderate to heavy levels. Measurements of Vc, mean transit time, arterial O2 tension (PaO2), and end tidal-arterial O2 tension difference (AaDO2) were made in 16 subjects (mean maximal oxygen uptake (VO2max) = 4.90 l.min-1) at rest and during five cycle exercise bouts designed to elicit 55, 65, 75, 85, and 95% VO2max. Mean PaO2 fell from 101 mm Hg at rest to 85 mm Hg during heavy exercise. Mean AaDO2 increased linearly from one stage to the next and at the highest work rate equaled 22.3 mm Hg. Mean Vc failed to plateau with increasing exercise intensity and increased on average by 16 ml from one stage to the next. Mean transit time, on average, dropped from 1.05 s at rest to 0.46 s at the lowest work rate. Mean transit time did not decrease further with increasing exercise intensity (range, 0.42-0.46 s). We conclude that, under the conditions of this study, the AaDO2 increases and PaO2 decreases observed in endurance athletes during exercise of increasing intensity is not caused by a plateau in Vc and a consequent reduction in mean transit time.

Sharp interface limit of a phase-field model of crystal grains.

We analyze a two-dimensional phase field model designed to describe the dynamics of crystalline grains. The phenomenological free energy is a functional of two order parameters. The first one reflects the orientational order, while the second reflects the predominantally local orientation of the crystal. We consider the gradient flow of this free energy. Solutions can be interpreted as ensembles of grains (in which the orientation is constant in space) separated by grain boundaries. We study the dynamics of the boundaries as well as the rotation of the grains. In the limit of an infinitely sharp interface, the normal velocity of the boundary is proportional to both its curvature and its energy. We obtain explicit formulas for the interfacial energy and mobility, and study their behavior in the limit of a small misorientation. We calculate the rate of rotation of a grain in the sharp interface limit, and find that it depends sensitively on the choice of the model.

Phase field modeling of electrochemistry. I. Equilibrium.

A diffuse interface (phase field) model for an electrochemical system is developed. We describe the minimal set of components needed to model an electrochemical interface and present a variational derivation of the governing equations. With a simple set of assumptions: mass and volume constraints, Poisson's equation, ideal solution thermodynamics in the bulk, and a simple description of the competing energies in the interface, the model captures the charge separation associated with the equilibrium double layer at the electrochemical interface. The decay of the electrostatic potential in the electrolyte agrees with the classical Gouy-Chapman and Debye-Hückel theories. We calculate the surface free energy, surface charge, and differential capacitance as functions of potential and find qualitative agreement between the model and existing theories and experiments. In particular, the differential capacitance curves exhibit complex shapes with multiple extrema, as exhibited in many electrochemical systems.

Phase field modeling of electrochemistry. II. Kinetics.

The kinetic behavior of a phase field model of electrochemistry is explored for advancing (electrodeposition) and receding (electrodissolution) conditions in one dimension. We previously described the equilibrium behavior of this model [J. E. Guyer, W. J. Boettinger, J. A. Warren, and G. B. McFadden, Phys. Rev. E 69, 021603 (2004)]. We examine the relationship between the parameters of the phase field method and the more typical parameters of electrochemistry. We demonstrate ohmic conduction in the electrode and ionic conduction in the electrolyte. We find that, despite making simple, linear dynamic postulates, we obtain the nonlinear relationship between current and overpotential predicted by the classical "Butler-Volmer" equation and observed in electrochemical experiments. The charge distribution in the interfacial double layer changes with the passage of current and, at sufficiently high currents, we find that the diffusion limited deposition of a more noble cation leads to alloy deposition with less noble species.

Accelerating Scientific Discovery Through Computation and Visualization.

The rate of scientific discovery can be accelerated through computation and visualization. This acceleration results from the synergy of expertise, computing tools, and hardware for enabling high-performance computation, information science, and visualization that is provided by a team of computation and visualization scientists collaborating in a peer-to-peer effort with the research scientists. In the context of this discussion, high performance refers to capabilities beyond the current state of the art in desktop computing. To be effective in this arena, a team comprising a critical mass of talent, parallel computing techniques, visualization algorithms, advanced visualization hardware, and a recurring investment is required to stay beyond the desktop capabilities. This article describes, through examples, how the Scientific Applications and Visualization Group (SAVG) at NIST has utilized high performance parallel computing and visualization to accelerate condensate modeling, (2) fluid flow in porous materials and in other complex geometries, (3) flows in suspensions, (4) x-ray absorption, (5) dielectric breakdown modeling, and (6) dendritic growth in alloys.

Maternal influences on growth and development of full-sibling foals.

Six pairs of full-sibling Quarter Horse foals were produced by non-surgical embryo transfer and immediate rebreeding of donor mares. Each pair of donor/recipient mares consisted of one multiparous (donor) and one nulliparous (recipient) mare of similar body type and size. Milk yield was determined within 2 d of 8, 15, 22, 29 d (early lactation); 45, 60 d (midlactation); and 90, 120 d (late lactation) postpartum by the weigh-suckle-weigh method. On the following day, milk samples were collected, and foals were weighed and measured for wither height, heart girth, metacarpal length, metatarsal length, carpus height, tarsus height, and hip height. Mean gestation length was longer (P < .05) in nulliparous mares than multiparous mares (343 vs 333 d). Daily milk production was greater (P < .05) during early lactation (12.1 vs 10.8 kg) and tended to be greater (P = .08) during midlactation (11.7 vs 10.4) in multiparous mares but was similar between groups in late lactation. Milk composition was similar between groups throughout lactation. Foals produced by multiparous mares weighed more (P < .03) throughout early lactation (70.4 vs 63.1 kg), but no differences in weights occurred between foals from multiparous and nulliparous mares through mid- and late lactation. Average daily weight gain (ADG) was similar between foal groups through early and midlactation. During late lactation, ADG tended to be greater (P = .07) in foals from nulliparous mares (1.05 vs .92 kg/d). These data suggest that nulliparous and multiparous mares of the same breed and similar body type and size produce foals with no differences in size and weight by 4 mo of age.

Interaction between auditory and oral sensory feedback in speech regulation.

To investigate the interaction between the auditory and oral sensory feedback modalities during speech production lingual vibrotactile thresholds were obtained from subjects in the following conditions: (1) before and after speech production with normal auditory feedback, (2) before and after speech production under exposure to auditory masking, and (3) before and after exposure to auditory masking without performing speech tasks. In addition duration measurements were obtained for selected speech sounds to investigate temporal changes in the articulatory patterns of subjects in the various conditions. Lingual sensory decreases and temporal reorganization were observed only in subjects speaking under auditory masking. These data suggest a balanced interaction between auditory and oral sensory feedback modalities which, when disturbed, results in non-phonemic change in speech production.