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.

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.

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.

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.

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.

Symptomatic solitary granular cell tumor of the trachea.

The granular cell tumor is a neoplasm that has generated considerable controversy. A rare case of solitary granular cell tumor located in the cervical trachea is described with a new mode of therapy using the carbon dioxide laser.

Surgical correction of late sequelae from facial bone fractures.

This study has described the UCLA experience over a 5 year period in the treatment of secondary traumatic deformities utilizing the craniofacial techniques originally proposed by Tessier. Because of scarring, absent parts, and the malposition of segments, correction of long-standing traumatic deformities remains difficult and treatment results remain less than ideal. Primary correction utilizing the principles we have described herein still provides the best functional and aesthetic results. Facial fractures can no longer be considered as an independent and unrelated entity when dealing with the traumatized patient. If primary reconstruction continues to be compromised, correction of residual disfigurement will result in unnecessary patient morbidity and disturbances of facial form and function.

Laryngeal tuberculosis as manifested in the decades 1963-1983.

Laryngeal tuberculosis is usually a complication of pulmonary tuberculosis and the clinical patterns have changed in recent decades. To evaluate the changing patterns, we reviewed 15 patients seen at the Massachusetts Eye and Ear Infirmary over a 20-year period and diagnosed as having laryngeal tuberculosis. The results showed a mean age of 56 years; a male predominance by a 2:1 ratio; minimal pulmonary lesions on radiographic studies in nine patients and one normal radiograph; clinical simulation by the tuberculous lesion of laryngeal cancer; excellent response to antituberculosis therapy; and low infectivity. Laryngeal lesions and concurrent pulmonary lesions should alert the otolaryngologist to consider systemic disease processes and the most frequent granulomatous lesion of the larynx, tuberculosis.

Management of mandibular fractures.

The complex physiology of the masticatory system is extremely sensitive to its intricate anatomic relationships. With the ever-increasing number of patients admitted to our institution with traumatic facial injuries, it seemed an appropriate time to evaluate the most widely employed treatment modalities available for the management of mandibular fractures. Maxillomandibular fixation remains the mainstay of mandible fracture stabilization. Within recent years, rigid internal fixation with miniplates and screws has become popular. This study compares the results of the most commonly used treatment modalities available for the repair of acute mandibular fractures.

Cysts and cyst-like lesions of the skin and subcutaneous tissue.

Cysts and cyst-like lesions are common occurrences seen in a busy plastic surgical practice. Although many can be treated by surgical excision, they still represent an interesting histologic, etiologic, embryologic, and clinical spectrum. In a number of instances, they require detailed multidiagnostic evaluation and complex surgical approaches to excision. By classifying these cystic masses by age group and anatomic location, the clinician can simplify his or her approach to this group of cutaneous masses.

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.

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.

Care of maxillofacial injuries: survey of plastic surgeons.

The purpose of this survey was to evaluate the current trends in the care of facial trauma. Data were obtained through the responses of a survey mailed to all those members and candidates listed in the 1989 American Society of Plastic and Reconstructive Surgeons Directory. A total of 2777 questionnaires were sent, with 1113 (40 percent) returned by means of a self-addressed envelope. Demographic results show that over 70 percent of the treating plastic surgeons fall within the age range 30 to 50 years. Although significant advances have occurred, treatment goals have remained unchanged. These center around the principles of accurate reduction and precise stabilization of fracture segments. The results of this survey reveal that a number of acceptable techniques were employed in the surgical repair of mandibular and zygomatic complex fractures. In the care of Le Fort III fractures, 59 percent of the respondents preferred the use of miniplates and screws for stabilization. Only 26.8 percent believed that facial fracture repair should be performed within the initial 24 hours. With frontal sinus fractures, the vast majority of plastic surgeons (82.1 percent) obtained a neurosurgical consultation. When the posterior wall was involved, 45.6 percent favored removal of the sinus mucosa, 29.7 percent obliterated the frontal sinus with a variety of autogenous materials, while 20.5 percent preferred cranialization. In summary, this survey shows a wide variation in the practice of facial fracture management within the plastic surgical community.

Surgical correction of exophthalmos secondary to Graves' disease.

Graves' disease has been recorded in the medical literature for more than 150 years. Despite introduction of iodine into the diet, Graves' disease still remains the most important disorder of the thyroid gland. Clinically, Graves' disease is a multisystem disorder of unknown etiology characterized by the clinical triad of infiltrative pretibial dermopathy, thyroid glandular hyperplasia, and ophthalmopathy. Expansion of the bony orbital volume is an effective method of treating moderate to severe exophthalmos. Our experience with a simplified version of a three-wall orbital decompression to correct exophthalmos secondary to Graves' disease is presented.

A histologic evaluation of fracture repair in the midface.

Although much has been written regarding the treatment of facial bone fractures, at the present time there are no available investigations of human microscopic sections to verify the exact nature of the healing process. The consensus in the literature is that following fractures of the midface, the bone segments are united by fibrous union. Biopsies of the healed fracture sites were obtained in 10 consecutive patients who underwent secondary reconstructive procedures to correct residual deformities. Clinical assessment confirmed that the fractures were completely healed and stable. Histologic sections were obtained across the healed fracture sites, sent for H&E staining, and then examined by light microscopy. All specimens showed that the defects between the segments were obliterated by the formation of a mature compact bone. This bridging bone was characterized by concentric lamellae surrounded by a typical bony architecture. From this study it can be concluded that fractures of the midface heal by direct bony union.

The effect of antenatal surgery on craniofacial growth in sheep model.

The purpose of this investigation was to evaluate the effect of antenatal palatal surgery in a sheep model. At 75 to 90 days of gestation, 20 fetuses underwent surgical in utero manipulation of their palates with the incision and elevation of bilateral bipedicled mucoperiosteal flaps. Sixteen of the 20 sheep (80 percent) went on to a normal full-term delivery. The palates and facial appearances were grossly evaluated, and detailed measurements were made of the palates. The data underwent statistical analysis. We were unable to discern any differences between the experimental group and the age-matched controls. Antenatal palatal surgery appeared to have no effect on craniofacial growth and development.

The submuscular aponeurotic system (SMAS): a histologic and comparative anatomy evaluation.

The submuscular aponeurotic system (SMAS) has been steeped in controversy. The goal of our anatomic study was to further clarify the existence of the SMAS. With an operating microscope, we performed dissections in 10 fresh cadaver heads (20 hemiheads) exposing the SMAS through a face lift incision. Through the operating microscope we were able to identify the SMAS and its relationship to other anatomic structures. Full-thickness longitudinal sections were obtained for routine histologic studies along various surgically relevant regions of the SMAS. In addition, dissections were accomplished with the operating microscope on 12 rhesus monkey fetuses ranging in age from a few weeks to 8 months. Data obtained from the fresh cadaver microdissections, topographic histology, and comparative anatomy revealed the presence of the SMAS as a distinct fibromuscular layer composed of the platysma muscle, parotid fascia, and fibromuscular layer covering the cheek.

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.

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.