The time course of muscle-tendon properties and function responses of a five-minute static stretching exercise.

The purpose of this study was to investigate the time course of the changes of muscle-tendon mechanical properties and the function responses of the plantar flexor muscles following 5 × 60 s of static stretching. Fourteen healthy volunteers were tested on four separate days in a random order with three different rest times (0, 5, 10 min) after 5 × 60 s of stretching or following a control period without stretching. During each test, the dorsiflexion range of motion (RoM), passive resistive torque (PRT), and maximum voluntary contraction (MVC) were measured with a dynamometer. Ultrasonography of the gastrocnemius medialis (GM) muscle-tendon junction displacement and motion capture allowed us to determine the length changes in the tendon and muscle, respectively, and hence to calculate their stiffness. We observed an increase in RoM and decrease in MVC at 0, 5, and 10 min post-stretching. This could be attributed to an increase in muscle elongation which lasted at least 10 min. A decrease in muscle-tendon stiffness was observed immediately, but not 5 or 10 min after the stretching. A decrease in PRT and muscle stiffness was observed up to 5 min after the stretching. No changes were detected in tendon stiffness or in any variable in the control group. The effects of a 5 × 60 s static stretching exercise changes the muscle-tendon functions (RoM, MVC), which are related to mechanical changes of the muscle but not the tendon structure, respectively. Although the functional changes last for at least 10 min, changes in muscle stiffness were only observed up to 5 min after the stretching exercise.

Dayside response of the magnetosphere to a small shock compression: Van Allen Probes, Magnetospheric MultiScale, and GOES-13.

Observations from Magnetospheric MultiScale (~8 Re) and Van Allen Probes (~5 and 4 Re) show that the initial dayside response to a small interplanetary shock is a double-peaked dawnward electric field, which is distinctly different from the usual bipolar (dawnward and then duskward) signature reported for large shocks. The associated E × B flow is radially inward. The shock compressed the magnetopause to inside 8 Re, as observed by Magnetospheric MultiScale (MMS), with a speed that is comparable to the E × B flow. The magnetopause speed and the E × B speeds were significantly less than the propagation speed of the pulse from MMS to the Van Allen Probes and GOES-13, which is consistent with the MHD fast mode. There were increased fluxes of energetic electrons up to several MeV. Signatures of drift echoes and response to ULF waves also were seen. These observations demonstrate that even very weak shocks can have significant impact on the radiation belts.

Electron densities inferred from plasma wave spectra obtained by the Waves instrument on Van Allen Probes.

The twin Van Allen Probe spacecraft, launched in August 2012, carry identical scientific payloads. The Electric and Magnetic Field Instrument Suite and Integrated Science suite includes a plasma wave instrument (Waves) that measures three magnetic and three electric components of plasma waves in the frequency range of 10 Hz to 12 kHz using triaxial search coils and the Electric Fields and Waves triaxial electric field sensors. The Waves instrument also measures a single electric field component of waves in the frequency range of 10 to 500 kHz. A primary objective of the higher-frequency measurements is the determination of the electron density ne at the spacecraft, primarily inferred from the upper hybrid resonance frequency fuh. Considerable work has gone into developing a process and tools for identifying and digitizing the upper hybrid resonance frequency in order to infer the electron density as an essential parameter for interpreting not only the plasma wave data from the mission but also as input to various magnetospheric models. Good progress has been made in developing algorithms to identify fuh and create a data set of electron densities. However, it is often difficult to interpret the plasma wave spectra during active times to identify fuh and accurately determine ne . In some cases, there is no clear signature of the upper hybrid band, and the low-frequency cutoff of the continuum radiation is used. We describe the expected accuracy of ne and issues in the interpretation of the electrostatic wave spectrum.

Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study.

We show the first evidence for locally excited chorus at frequencies below 0.1 fce (electron cyclotron frequency) in the outer radiation belt. A statistical study of chorus during geomagnetic storms observed by the Van Allen Probes found that frequencies are often dramatically lower than expected. The frequency at peak power suddenly stops tracking the equatorial 0.5 fce and f/fce decreases rapidly, often to frequencies well below 0.1 fce (in situ and mapped to equator). These very low frequency waves are observed both when the satellites are close to the equatorial plane and at higher magnetic latitudes. Poynting flux is consistent with generation at the equator. Wave amplitudes can be up to 20 to 40 mV/m and 2 to 4 nT. We conclude that conditions during moderate to large storms can excite unusually low frequency chorus, which is resonant with more energetic electrons than typical chorus, with critical implications for understanding radiation belt evolution.

Baby sleeping bag and conventional bedding conditions--comparative investigations by infrared thermography.

BACKGROUND: Thermal stress is a risk factor for sudden infant death syndrome (SIDS). Recently, baby sleeping bags have been recommended as a preventive measure against SIDS. The aim of this study was to describe in which way the use of baby sleeping bags might influence thermoregulation of sleeping infants and maybe the incidence of SIDS. METHODS: Body surface temperature was recorded by use of infrared thermography in 15 infants (median age 49 days). Recordings were done twice: after sleeping for 60 min under a blanket and after sleeping for 60 min in a baby sleeping bag. Temperature was recorded and compared for defined sites of body surface. RESULTS: Infants' mean body surface temperature as well as core temperature after sleeping in a baby sleeping bag did not show significant differences when compared to infants sleeping under a conventional blanket. CONCLUSION: Under controlled conditions, core temperature and mean body surface temperature are comparable, equally if using a baby sleeping bag or conventional bedding. However, under the more uncontrolled conditions of baby care at home, sleeping bags might provide a more constant temperature profile, while other bedding conditions may lead to significant variations of temperature pattern.

An improved method to determine neuromuscular properties using force laws - From single muscle to applications in human movements.

We evaluate an improved method for individually determining neuromuscular properties in vivo. The method is based on Hill's equation used as a force law combined with Newton's equation of motion. To ensure the range of validity of Hill's equation, we first perform detailed investigations on in vitro single muscles. The force-velocity relation determined with the model coincides well with results obtained by standard methods (r=.99) above 20% of the isometric force. In addition, the model-predicted force curves during work loop contractions very well agree with measurements (mean difference: 2-3%). Subsequently, we deduce theoretically under which conditions it is possible to combine several muscles of the human body to model muscles. This leads to a model equation for human leg extension movements containing parameters for the muscle properties and for the activation. To numerically determine these invariant neuromuscular properties we devise an experimental method based on concentric and isometric leg extensions. With this method we determine individual muscle parameters from experiments such that the simulated curves agree well with experiments (r=.99). A reliability test with 12 participants revealed correlations r=.72-.91 for the neuromuscular parameters (p<.01). Predictions of similar movements under different conditions show mean errors of about 5%. In addition, we present applications in sports practise and theory.

The relation between Hill's equation and individual muscle properties.

In this paper we deal with movement-independent individual muscle properties derived from Hill's equation. Relations between these properties are found by theoretical considerations. We define a dimensionless quantity that turns out to play a major role in characterizing individual muscle properties, and we analyse normalization and symmetry behaviour of the parameters in Hill's equation. This leads to a systematic, transparent, and useful overview of mathematical relations involving muscle parameters. We examine the experimentally determined parameters of 62 subjects to find additional empirical relations between the muscle properties described by the parameters of Hill's equation. In the light of the theoretical end empirical results we investigate the connections between maximum efficiency, endurance, and fibre composition.

New directions in the management of cleft lip.

Advances in cleft lip and palate have included improved understanding of its etiopathogenesis, genetics, and the surgical evolution of technical refinements in the correction of this deformity.

Abdominal wall closure after intestinal transplantation.

Successful surgical closure of the abdominal wall after either combined or isolated intestinal transplantation may present a challenging dilemma for the plastic and reconstructive surgeon because of the following factors: restricted volume of the recipient abdominal cavity; donor-recipient size discrepancies as expressed by the donor to recipient weight ratio; and significant intraoperative edema. The purpose of this investigation is to present clinical experience with 51 consecutive patients who underwent a total of 57 sequential intestinal transplantations at the University of Miami-Jackson Memorial Hospital. A retrospective chart review of 36 pediatric (63 percent) and 21 adult (37 percent) transplantations was performed. Age of the pediatric population ranged from 1 month to 13 years (mean, 2.4 years) and of the adult population from 22 to 55 years (mean, 33.5 years). Several diagnostic classifications necessitated organ transplantation. Because of insufficient donor graft size for the recipient abdominal cavity in 19 transplantations (33 percent), several technical modifications were used to achieve anatomic and functional abdominal wall closure in all patients. In summary, the plastic and reconstructive surgeon should have a significant role in the comprehensive planning and management of abdominal wall closure in this challenging group of patients.

Priorities in the treatment of facial fractures for the millennium.

Although certain principles for management of facial fractures have not changed, new avenues reach this goal with greater precision and less morbidity. By reviewing these recent developments one can see the enormous potential for future developments in technology, techniques, and biomaterials. Development of tertiary care centers for the multiple trauma victim has improved management of facial trauma by bringing a large experience to a team of individuals where creativity flourishes. Major leaps in diagnostic skills and technology now allow us to answer some to the controversial treatment issues in facial trauma. This article hopes to review some old concepts and look at new approaches in managing facial fractures.

Approaches to cleft lip and palate repair.

Facial clefts remain one of the most common congenital anomalies encountered by plastic surgeons. Over the last few decades, surgical results have continued to improve due to the interdisciplinary approach to this complex clinical problem.

Patterns of maxillofacial injuries in powered watercraft collisions.

Because of the widespread popularity of water sports, plastic and reconstructive surgeons can expect to manage an increasing number of injuries associated with these activities, particularly those related to powered watercraft vehicles. Although seat belts for motorists and helmets for motorcyclists may be efficacious, such devices currently do not serve a similar role in powered watercraft sports. In this study, a retrospective chart review of 194 consecutive patients who presented to the University of Miami/Jackson Memorial Hospital (Level I trauma center) as a result of powered watercraft collisions is presented. The purpose of this investigation was to assess the incidence, cause, demographics, and available management options for head and neck injuries secondary to powered watercraft. Identified were 194 patients who presented because of watersports-related injuries during the period January 1, 1991, through December 31, 1996. From this group, 81 patients (41.8 percent) sustained injuries directly attributable to powered watercraft collisions, including 41 personal watercraft collisions (50.6 percent), 39 boat collisions (48.1 percent), and 1 airboat collision (1.2 percent). The patient population, as expected, tended to be young and male with an average age of 29 years (range, 8 to 64 years old). Interestingly, 41 of the patients (50.6 percent) who presented to this trauma center as a result of powered watercraft collisions also sustained associated head and neck trauma. Of 74 injuries 24 were facial fractures (32.4 percent), 18 were facial lacerations (24.3 percent), 14 were closed head injuries (18.9 percent), 8 were skull fractures (10.8 percent), 4 were scalp lacerations (5.4 percent), 4 were C-spine fractures (5.4 percent), 1 was an ear laceration (1.4 percent), and 1 was a fatality (1.4 percent). Le Fort fractures were the most commonly identified facial fracture in this series. The number of these injuries seen in hospital emergency rooms will most likely increase in the future as the popularity of water-related recreational activities becomes even more widespread. Based on these findings, it is strongly recommended that future efforts be directed toward the prevention of these injuries through patient education and the eventual development of efficacious and safe protective equipment.

Maxillofacial injuries in women.

Although maxillofacial injuries account for a large number of hospital admissions, there appear to be only a few reports detailing the etiology and pattern of facial injuries in women. To delineate this problem, we performed a retrospective chart review of all women admitted to University of California, Davis Medical Center with traumatic facial injuries from July 1, 1990, to June 30, 1992. Motor vehicle accidents were the primary etiology, followed by assaults. The mandible was the most commonly injured facial bone. In a closer evaluation of female patients injured by assault, we found inadequate documentation describing the circumstances surrounding their facial injuries. This indicates that domestic violence and other forms of assaults against women may be severely underreported and has important implications for health care professionals who must always suspect physical abuse in any woman who presents with maxillofacial injuries without an obvious, known etiology.

Complications of mandibular fractures.

Timely repair of mandibular fractures remains an effective means to reduce pain, restore function, and prevent complications. This study addresses the effect of the time interval between injury and treatment on the overall complication rate, the complication rate between various treatment modalities (mandibular-maxillary fixation [MMF] alone, MMF with intraosseous wire bone fixation, and MMF with rigid internal fixation), and the relationship of inpatient vs. outpatient management. Cost was also examined with respect to choice of management. We report a retrospective series of 308 consecutive patients managed at the University of Miami/Jackson Memorial Hospital. Patients who received treatment 3 to 10 days following injury were found to have a lower complication rate than earlier or later repair. We postulate that most patients with mandibular fractures may be managed on an outpatient basis, which represents a considerable savings in cost.

Effect of insulin-like growth factor type I on critical size calvarial bone defects in irradiated rats.

Irradiated wounds are characterized by a slow healing process. Insulin-like growth factor-1 (IGF-1), a somatomedin C, has been shown in previous studies to stimulate collagen synthesis and bony repair. The purpose of this investigation is to evaluate the potential beneficial effects of recombinant IGF-1 in the healing of critical size calvarial defects in previously irradiated adult male Sprague-Dawley rats.

Holmium YAG laser-assisted osteotomies in plastic and reconstructive surgery: a preliminary report.

An Omnipulse holmium-yttrium aluminum garnet (YAG) laser was used to assist in the harvesting of outer table or split calvarial bone grafts in cadaver skulls. Two- or 4-mm depth and 0.55-mm width holes in the outer cortex of cadaveric calvarium were formed without apparent gross periosteal or bony injury. Osteotomes were then used to shave or split calvarial grafts by connecting the 2- and 4-mm depth holes, respectively. The procedure was efficient as well as precise. We believe that this method of bone graft harvesting may have the added benefit of safety by decreasing the incidence of inadvertent dural penetration. This study will lead to further analysis of the potential use for additional bony work with the Omnipulse holmium-YAG laser.

Bregmatic masses in children.

Bregmatic masses often present a challenging diagnostic dilemma. We present two illustrative cases to demonstrate this clinical problem and present our recommendations for evaluation and treatment.

Bregmatic epidermoid inclusion cyst eroding both calvarial tables.

Dermoid and epidermoid cysts are uncommon masses in the head and neck region of children. Although the most common location of inclusion cysts in the head and neck is the bregma, masses in this region must be differentiated from midline hemangiomas, lipomas, hematomas, or encephaloceles. Inclusion cysts should be considered in the differential diagnosis of all midline cystic lesions in infants, because, if left untreated, it may lead to devastating complications. We present the case of a slowly enlarging midline mass in a female infant to illustrate the potential for serious sequelae from inclusion cysts.

Cranial bone grafting: biodegradable versus titanium fixation in a rabbit model.

Rigid internal fixation with miniplates and screws has enabled reconstructive surgeons to position bony segments precisely. Unfortunately, our present systems have been associated with a potential adverse effect on ultimate craniofacial growth and development. Also, they may be palpable, necessitating secondary procedures for removal of the hardware. We have been involved in an ongoing study evaluating the efficacy of a commercially developed biodegradable system. In this study, we compared biodegradable lag screw fixation with traditional titanium screw fixation in full-thickness, membranous bone grafts harvested from the zygomatic arches to the snout in a rabbit model. The results were compared with standard hematoxylin and eosin stains and laser densometry. Although this study adds further credence to the resorption of bone grafts, those secured with the polyglycolic acid screws demonstrated significantly less resorption than those maintained in position by traditional methods.

The residual cleft lip nasal deformity. An anatomic approach.

The cleft lip nasal deformity presents an extremely challenging problem for the reconstructive surgeon. Consistent satisfactory results have been difficult to attain. This article demonstrates that by obtaining sufficient exposure, each abnormal component can be identified and appropriately reconstructed.