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Purpose In recent years, a growing trend toward clinical doctorate degrees has emerged in several allied health professions. However, few studies have been conducted within the physician assistant (PA) profession related to changing the entry-level degree for PAs to a clinical doctorate. Methods A descriptive, quantitative study assessing PA students' perceptions of changing the entry-level credential for PAs to a clinical doctorate was conducted. Thirty randomly selected programs with 1,966 students were invited to participate in the survey. Results Of the programs invited, 25 (83%) participated, with 486 (25%) full-time students completing the survey. Of the respondents, 56.1% (272) were first-year students and 43.9% (213) were second-year students. Both groups had a negative perception of changing the entry-level degree for PAs to a clinical doctorate, indicating the doctorate will raise the cost of PA education and discourage some people from entering the profession (82.1%, n = 398); a doctorate for PAs will cause confusion for patients (71.3%, n = 346); and that there is no need for the profession-specific doctorate since the master's degree sufficiently prepares PAs to practice in today's health care setting (70.9%, n = 344). Conclusions The present findings lend additional support to previous studies, endorsing the master's degree as the entry-level and terminal degrees.

The Transiting Exoplanet Survey Satellite (TESS) is an MIT-led, NASA-funded Explorer-class planet finder launched in April 2018. TESS will carry out a 2-year all-sky survey with the primary goal of detecting small transiting exoplanets around bright and nearby stars. The TESS instrument consists of four wide-field cameras in a stacked configuration, providing a combined field of view of 24 deg × 96 deg that spans approximately from the ecliptic plane to the ecliptic pole. In order to achieve the desired photometric precision necessary for the mission, TESS uses the instrument cameras as star trackers during fine-pointing mode to enhance attitude accuracy and stabilization for science operations. We present our approach in quantifying the expected performance of the fine-pointing system and assessing the impact of pointing performance on the overall photometric precision of the mission. First, we describe the operational details of the fine-pointing system with the science instrument being used for star-tracking. Next, we present the testing framework used to quantify the attitude determination performance of the system and the expected attitude knowledge accuracy results, both in coarse-fine pointing hand-off and in nominal fine-pointing conditions. By combining simulations of the instrument and the spacecraft bus, we quantify the closed-loop fine-pointing stability performance of the system in nominal science operations as well as in the case of camera unavailability due to Earth/Moon interference. Finally, we assess the impact of platform pointing stability on the photometric precision of the system using detailed system modeling and discuss the applicability of mitigation techniques to reduce the effect of jitter on TESS science data.

The rapidly growing automobile industry increases the accumulation of end-of-life tires each year throughout the world. Waste tires lead to increased environmental issues and lasting resource problems. Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of society. A patented sulfonation process followed by pyrolysis at 1100 &deg, C in a nitrogen atmosphere was used to produce carbon material from these tires and utilized as an anode in lithium-ion batteries. The combustion of the volatiles released in waste tire pyrolysis produces lower fossil CO2 emissions per unit of energy (136.51 gCO2/kW&middot, h) compared to other conventional fossil fuels such as coal or fuel&ndash, oil, usually used in power generation. The strategy used in this research may be applied to other rechargeable batteries, supercapacitors, catalysts, and other electrochemical devices. The Raman vibrational spectra observed on these carbons show a graphitic carbon with significant disorder structure. Further, structural studies reveal a unique disordered carbon nanostructure with a higher interlayer distance of 4.5 &Aring, compared to 3.43 &Aring, in the commercial graphite. The carbon material derived from tires was used as an anode in lithium-ion batteries exhibited a reversible capacity of 360 mAh/g at C/3. However, the reversible capacity increased to 432 mAh/g at C/10 when this carbon particle was coated with a thin layer of carbon. A novel strategy of prelithiation applied for improving the first cycle efficiency to 94% is also presented.

Micro-X is a sounding-rocket experiment that will combine a transition edge sensor (TES) microcalorimeter array with an imaging mirror to obtain high-spectral-resolution images of astronomical X-ray sources. The instrument's resolution across the 0.3-2.5 keV band will be 2 eV. The first flight will target the region of the Bright Eastern Knot of the Puppis A supernova remnant and is slated for January 2011. The obtained high-resolution X-ray spectra will be used to ascertain the temperature and ionization state of the X-ray-emitting gas and to determine its velocity structure. The TES array is read out by a time-division superconducting quantum interference device (SQUID) multiplexing system. The detector front end assembly and the SQUID multiplexing circuit are cooled to the operating temperature of 50 mK with an adiabatic demagnetization refrigerator (ADR). The design of this refrigerator is tailored to the requirements of rocket flight. Stable operation of the TES array close to the ADR magnet will be achieved with a magnetic shielding system, which will be based on a combination of a bucking coil and high-permeability and superconducting shield materials to cancel out residual fields. We describe our progress in developing the Micro-X instrument.

Hypofractionated stereotactic radiosurgery allows the treatment of metastatic and primary spinal tumors with highly conformal dosing while sparing the adjacent neural structures. This enables the physician to treat tumors which are recurrent after standard external beam radiation, are radioresistant in doses normally tolerated by the spinal cord or are in patients with primary tumors who are not candidates for surgical resection. Initial results have shown satisfactory achievement of treatment goals with minimal occurrence of complications.

Objective Spinal sarcomas pose unique treatment dilemmas because of the difficulty of achieving adequate surgical margins and/or delivering curative radiation doses (65 Gy) in close proximity to the spinal cord. This study used hypofractionated stereotactic radiosurgery (SRS) to deliver higher biologically effective doses to treat primary spinal sarcomas and spinal sarcoma metastases. Methods Twenty-four patients with spinal or paraspinal sarcomas entered an Institutional Review Board-approved registry trial to evaluate SRS efficacy. They were assessed at regular intervals for pain control, disease progression, and complications for a minimum of 12 months or until death. Results The median treatment dose for the spinal sarcoma lesions was 30 Gy at the 80% isodose in 3 fractions, with some variation based on tumor size, shape, and dose to adjacent critical structures. Seven patients were treated definitively; all had excellent pain relief and are alive with a mean follow-up period of 33 months. Two patients had complete tumor regression, 3 had partial regression, and 2 experienced recurrences and have been re-treated. Seven patients underwent resection and adjuvant SRS. One of 3 patients treated preoperatively had complete tumor regression, and none of the 4 patients treated postoperatively had a local recurrence with a mean follow-up period of 43.5 months. All 10 patients with sarcoma metastases to the spine (16 lesions) died, with a mean survival of 11.1 months from first spinal metastasis treatment. Complete pain relief was achieved in 8 patients, partial relief in 7 patients, and none in 1 patient. No patient developed radiation myelitis. Conclusion These preliminary results suggest that SRS may have a role in the definitive treatment of patients with primary spinal sarcomas who are deemed unresectable and as adjuvant treatment in those undergoing surgery and for palliation of sarcoma metastases.

Objective:The purpose of this study was to examine young women's urinary incontinence knowledge.Study design:Descriptive.Background:Urinary incontinence is a disorder that is linked to pregnancy and childbirth. It is a subject of an unmentionable nature as it is related to the reproductive a

The treatment of patients with cancer epitomizes the importance of using a collaborative team approach to optimize patient care. Physician team members most commonly are radiation oncologists, general surgeons, surgical oncologists, thoracic surgeons, neurosurgeons, and orthopedic surgeons. When patients are receiving chemotherapy, their medical oncologist frequently takes responsibility for coordinating care among the various team members and initiating consultations with necessary providers. When patients develop bone metastases or chemotherapy-induced bone loss (CTIBL), the orthopedic surgeon may be able to improve the patient's quality of life greatly. Procedures orthopedists perform most commonly include open reduction and internal fixations and arthroplasties (joint replacement surgery). Less invasive procedures currently being tested include stereotactic radiosurgery, radiofrequency ablation (RFA), and percutaneous cementoplasty. By understanding the options available to patients with skeletal complications of malignancy, the medical oncologist can discuss issues with patients and make appropriate referrals for diagnosis and treatment. Additionally, with a greater understanding of the surgical procedures available, the medical oncologist will be better able to assist in preparing the patient for surgery.

Airway responses were compared following 6-minute eucapnic voluntary hyperventilation and 6-minute exercise challenges by examining resting and post-challenge impulse oscillometry and spirometry variables. Twenty-two physically active individuals with probable exercise-induced bronchoconstriction took part in this study. Impulse oscillometry and spirometry were performed at baseline and for 20 minutes post-challenge at 5-minute intervals. High correlation was found between the two measures of change in airway function for both methods of challenge. Impulse oscillometry detected a difference in degree of response to the challenges, whereas spirometry indicated no difference, suggesting that impulse oscillometry is a more sensitive measure of change in airway function.

Study objective The efficacy of using impulse oscillometry (IOS) as an indirect measure of airflow obstruction compared to spirometry after exercise challenges in the evaluation of exercise-induced bronchoconstriction (EIB) has not been fully appreciated. The objective was to compare airway responses following room temperature and cold temperature exercise challenges, and to compare whether IOS variables relate to spirometry variables. Design Spirometry and IOS were performed at baseline and for 20 min after challenge at 5-min intervals. Setting Two 6-min exercise challenges, inhaling either room temperature (22.0°C) or cold temperature (− 1°C) dry medical-grade bottled air. At least 48 h was observed between these randomly assigned challenges. Participants Twenty-two physically active individuals (12 women and 10 men) with probable EIB. Interventions Subjects performed 6 min of stationary cycle ergometry while breathing either cold or room temperature medical-grade dry bottled air. Subjects were instructed to exercise at the highest intensity sustainable for the duration of the challenge. Heart rate and kilojoules of work performed were documented to verify exercise intensity. Measurements and results Strong correlations were observed within testing modalities for post-room temperature and post-cold temperature exercise spirometry and IOS values. Spirometry revealed no differences in postexercise peak falls in lung function between conditions; however, IOS identified significant differences in respiratory resistance (p Conclusions Correlations were found between spirometric and IOS measures of change in airway function for both exercise challenges, indicating close equivalency of the methods. The challenges appeared to elicit the EIB response by a similar mechanism of water loss, and cold temperature did not have an additive effect. IOS detected a difference in degree of response between the temperatures, whereas spirometry indicated no difference, suggesting that IOS is a more sensitive measure of change in airway function.

Cold Air Inhalation Does Not Affect the Severity of EIB after Exercise or Eucapnic Voluntary Hyperventilation. Med. Sci. Sports Exerc., Vol. 37, No. 4, pp. 544-549, 2005. Introduction: Exercise-induced bronchoconstriction (EIB) is thought to result from osmotic and thermal events of air conditioning during exercise at high ventilation rates. The purpose of this study was to evaluate lung function after exercise and eucapnic voluntary hyperventilation (EVH) while breathing both room-temperature and cold-temperature dry bottled air. Methods: Twenty-two subjects were identified as EIB probable by a fall of ≥7% in forced expiratory volume in the first second of exhalation (FEV 1 ) using a 6-min room-temperature EVH challenge (RTEVH; 22.0°C). Subjects then randomly performed three 6-min challenges: cold-temperature EVH (CTEVH; -1°C), room-temperature exercise (RTEX; 22.0°C), and cold-temperature exercise (CTEX; -1°C), with a period of at least 48 h observed between challenges. Spirometry was performed at baseline and at 5, 10, 15, and 20 min postchallenge. Results: Reasonable agreement was found between challenge modes and room-temperature and cold-temperature challenges. Postchallenge percent falls in FEV 1 were -15.21, -13.80, -13.12, and -10.69 for RTEVH, CTEVH, RTEX, and CTEX, respectively. RTEVH resulted in a significantly greater percent fall in FEV 1 than CTEX (P = 0.048); no other differences in FEV 1 were observed. Conclusion: Similar postchallenge percent falls in FEV 1 for room- and cold-temperature EVH and exercise suggest that dryness is essential to test conditions, as cold temperature did not have an additive effect to the EIB response.

To determine the imaging characteristics of soft-tissue myxoma, with emphasis on computed tomographic (CT) and magnetic resonance (MR) imaging findings and pathologic comparison.Records of 45 pathologically confirmed soft-tissue myxomas in 44 patients were retrospectively reviewed. Patient demographics and radiographs (n = 20), bone scintigrams (n = 2), angiograms (n = 3), and ultrasonographic (US) (n = 6), CT (n = 14), and MR images (n = 33) were evaluated by two musculoskeletal radiologists with agreement by consensus for lesion location, lesion size, and intrinsic characteristics.Soft-tissue myxoma more commonly affected women (59%; average age 52 years) and manifested as a slowly enlarging (64%) painful (51%) mass. Lesions were most frequently intramuscular (82%) and involved the thigh (51%). An appearance similar to that of a cyst was seen at CT (at which the lesions demonstrated low attenuation) and at MR imaging (at which the lesions demonstrated markedly high signal intensity on T2-weighted images) in all cases because of the high water content of mucin that was seen histologically. The true solid architecture of these lesions was best depicted in all cases at US (at which the lesions were hypoechoic, not anechoic) and on MR images obtained with contrast material (at which the lesions demonstrated internal enhancement). A small amount of tissue similar to fat surrounding these intramuscular myxomas (71% at MR imaging) corresponded histologically (70%) to atrophy of surrounding muscle.Soft-tissue myxoma often demonstrates characteristic US, CT, and MR imaging findings, including intramuscular location, intrinsic high water content, and a surrounding rim of fat.

Satisfaction with fitness facilities has long been accepted as a positive contributing factor to physical activity, readiness, and overall quality of life for military families. Our findings are based on a random sample of military families surveyed at 38 installations worldwide and at remote locations. A total of 8,572 service member and 3,493 spouse (55% and 32% response rate, respectively) questionnaires were completed and returned. Overall, members were satisfied with fitness facilities and programs, but spouses were less satisfied and more unfamiliar with these facilities. Most valued programs were fitness centers and swimming pools. Members reported that elimination of fitness facilities would greatly decrease the quality of life on installations, particularly at sites outside the continental United States, whereas spouses reported that this would not have a dramatic effect. The results of this study could be used to direct funding allocations, improve the health and fitness of military families, and suggest areas for further research.

This prospective clinical study was undertaken to evaluate the effect of spontaneous food/fluid intake on serum sodium and comfort levels in a population of terminal patients (n = 31) receiving clysis or intravenous hydration. The median and mode of serum sodiums were within normal limits and 56 percent of the patients were eunatremic. There was no statistically significant difference in comfort scores between predehydration and dehydration phases, and 85 percent had an optimal comfort score. A statistically significant difference was found (p < 0.5) between mean daily comfort scores of those with normal sodiums versus those with abnormal sodiums; those with hypernatremia were lower but still in the top third comfort levels. Because the sodium was tested using a Chem7, we also were able to calculate the BUN, creatinine, and osmolality. These are presented and compared to other study results. The findings of this study reinforce the belief that fluid depletion in dying patients results in relatively benign symptoms, that serum sodium levels are not always altered with limited intake and that comfort levels can be maintained when the serum sodium is abnormal.

Fractures of the sacrum are infrequent injuries; however, they comprise a wide spectrum of injury types.Classification of the injuries are predominantly by fracture line direction (vertical, transverse, and oblique). The direction of the fracture line dictates both the most effective type of surgical management as well as the biologic consequences of the fracture. Most vertical fractures are associated with pelvic injuries and rarely have severe neural conpromise. Fixation of the sacral fracture is often a part of the more complex restoration of pelvic stability. Transverse and oblique sacral fractures are less often part of a pelvic injury complex; and they more often have associated neural deficits. Surgical treatment is most often indicated for neural decompression and stabilization for optimal recovery.

Background We reviewed our experience using anterior thoracoscopic procedures in the correction of severe idiopathic scoliosis and kyphotic deformities to evaluate the feasibility and effectiveness of such procedures. Study design Twenty-four patients who underwent thoracoscopic surgical correction of the spine between March 1995 and December 2001 were retrospectively reviewed. A team consisting of one orthopaedic surgeon and one thoracic surgeon performed anterior thoracoscopic soft tissue release, disc excision, and bone grafting followed on the same day with posterior instrumentation and correction of deformity. Results There were 16 female and 8 male patients, with a median age of 16 years (range 11 to 47 years) with idiopathic scoliosis (20 patients) or kyphotic deformity (4 patients). The average time for the thoracoscopy was 125 minutes (range 60 to 175 minutes). Blood loss averaged 135 mL (range 20 to 350 mL), and a median number of five discs (range two to eight) were excised. The median ICU time was 2 days (range 1 to 8 days), and the median length of hospital stay was 6 days (range 4 to 11 days). One patient required conversion to an open procedure because of arterial bleeding from the cancellous bone (T5). Postoperative complications occurred in four patients (atelectasis, pneumothorax, pneumonia, and wound infection in one patient each). All patients had an uneventful hospital course after treatment. Conclusions Thoracoscopic anterior procedures can be used safely and effectively in the treatment of idiopathic scoliosis and kyphotic deformity. This minimally invasive approach might decrease procedure-related trauma, operative time, blood loss, and length of hospitalization and may also alleviate postthoracotomy pain.

The properties and outcome of an immune response are best predicted by the lymphokine phenotype of the responding T cells. Cytokines produced by CD4+ T helper type 1 (Th1) T cells mediate delayed type hypersensitivity (DTH) and inflammatory responses, whereas cytokines produced by Th2 T cells mediate helper T cell functions for antibody production. To determine whether induction of Th2-like cells would modulate an inflammatory response, interleukin 4 (IL-4) was administered to animals with experimental allergic encephalomyelitis (EAE), a prototypic autoimmune disease produced by Th1-like T cells specific for myelin basic protein (MBP). IL-4 treatment resulted in amelioration of clinical disease, the induction of MBP-specific Th2 cells, diminished demyelination, and inhibition of the synthesis of inflammatory cytokines in the central nervous system (CNS). Modulation of an immune response from one dominated by excessive activity of Th1-like T cells to one dominated by the protective cytokines produced by Th2-like T cells may have applicability to the therapy of certain human autoimmune diseases.

We have developed a high-resolution alignment technique which utilizes the partial polarization property of fine period transmission gratings. It is especially useful when the grating period is sufficiently small so that there are no visible diffracted orders. This technique uses a photoelastic modulator (PEM) to produce an intensity signal that is proportional to the sine of twice the angle between the grating lines and the PEM crystal axis. The experimentally demonstrated resolution of this technique on 200-nm period gold transmission gratings is better than 1 sec of arc. This technique was developed to align x-ray transmission gratings for spectroscopy and interferometry applications.

The Advanced X-ray Timing Array (AXTAR) is a mission concept for X-ray timing of compact objects that combines very large collecting area, broadband spectral coverage, high time resolution, highly flexible scheduling, and an ability to respond promptly to time-critical targets of opportunity. It is optimized for submillisecond timing of bright Galactic X-ray sources in order to study phenomena at the natural time scales of neutron star surfaces and black hole event horizons, thus probing the physics of ultradense matter, strongly curved spacetimes, and intense magnetic fields. AXTAR's main instrument, the Large Area Timing Array (LATA) is a collimated instrument with 2-50 keV coverage and over 3 square meters effective area. The LATA is made up of an array of supermodules that house 2-mm thick silicon pixel detectors. AXTAR will provide a significant improvement in effective area (a factor of 7 at 4 keV and a factor of 36 at 30 keV) over the RXTE PCA. AXTAR will also carry a sensitive Sky Monitor (SM) that acts as a trigger for pointed observations of X-ray transients in addition to providing high duty cycle monitoring of the X-ray sky. We review the science goals and technical concept for AXTAR and present results from a preliminary mission design study., Comment: 19 pages, 10 figures, to be published in Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray, Proceedings of SPIE Volume 7732

To explore the relationship between surgical approach and chronic posterior iliac crest donor site pain, 151 bone graft harvests with follow-up periods longer than 1 year were evaluated using a detailed questionnaire and follow-up clinical visits. There was no difference in the incidence of chronic donor site pain between harvests performed through the primary midline incision versus a separate lateral oblique incision (28 vs 31%). Twice as many donor sites harvested for reconstructive spinal procedures were reported as having chronic pain as compared with those harvested for spinal trauma, regardless of approach used (39 vs 18%). The association of chronic donor site pain with residual back pain was also greater in the spinal reconstructive group. Thus, it appears that incidence of chronic donor site pain is more dependent on diagnosis than on surgical approach.

Fracture separations of the articular mass are a specific group of unilateral facet fractures that must be considered separately because of their unique two-level instability. This fracture pattern involves a longitudinal fracture of the lamina and a fracture of the pedicle on the same side of the spine at the same level. It is characterized roentgenographically by horizontalization of the lateral mass, with a mean translation of 4.6 mm and a mean angulation of 6.9 degrees. In this study the deformity most commonly occurs at the level below the fracture (19 patients) but also occurred at the level above (5 patients). There is a high incidence of neurologic involvement (14 of 24 patients), most often radicular in nature. This injury results in two level instability requiring a three-level, two-interspace stabilization. All twenty-four patients in this series underwent posterior cervical plating with either an asymmetric (8), symmetric (9) or porte manteau (7) construct. Statistically significantly better results (P < 0.05) were achieved with either a symmetric or porte manteau construct. Complications including neurologic deficit and loss of correction were more frequent in the asymmetric group.

Metastatic disease from osteosarcoma most commonly occurs in the lung and bony sites. Both primary spinal osteosarcomas and spinal metastatic lesions are rare. A case is reported of a nonosseous epidural metastatic lesion from osteosarcoma. It was visualized best by metrizamide-enhanced computed tomographic scanning. The patient symptomatically improved with excision of the lesion although there was massive recurrence despite combined therapy.

We present a spectrometer design based on a novel nanofabricated blazed X-ray transmission grating which is modeled to have superior efficiency. Here we outline a full instrument design proposed for Constellation-X which is expected to give resolving powers ~2000 (HEW). The spectrometer advantages include lower mass budget and smaller diffractor area, as well as order-of-magnitude more relaxed alignment tolerances for crucial degrees of freedom than reflection grating schemes considered in the past 1,2,3 . The spectrometer readout is based on conventional CCD technology adapted to operate with very high speed and low power. This instrument will enable high resolution absorption and emission line spectroscopy in the critical band between 0.2 and 1.5 keV.

BAUMANN, J. M., K. W. RUNDELL, T. M. EVANS, and A. M. LEVINE. Effects of Cysteine Donor Supplementation on Exercise-Induced Bronchoconstriction. Med. Sci. Sports Exerc., Vol. 37, No. 9, pp. 1468 –1473, 2005. Purpose: Reactive oxygen/ nitrogen species (ROS/RNS) in resident airway cells may be important in bronchoconstriction following exercise. Glutathione (GSH) is a major lung antioxidant and could influence pathological outcomes in individuals with exercise-induced bronchoconstriction (EIB). This study examined the effects of supplementation with undenatured whey protein (UWP) in subjects exhibiting airway narrowing following eucapnic voluntary hyperventilation (EVH), a surrogate challenge for diagnosis of EIB. UWP is a cysteine donor that augments GSH production. Methods: In a randomized, double-blind, placebo-controlled study, 18 EIB-positive subjects (age: 25.2 9.01 yr; weight: 77.3 18.92 kg; height: 1.7 0.09 m) with post-EVH falls of 10% in FEV1 received 30 g UWP (TX) or casein placebo (PL)/d. Subjects performed 6-min EVH challenges before and after 4 and 8 wk of supplementation. Exhaled nitric oxide (eNO) was measured serially before spirometry and at 1-wk intervals. Spirometry was performed pre- and 5, 10, and 15 min postchallenge Results: Subjects exhibited significant mean improvement in postchallenge falls in FEV1 from 0w k (22.6 12.22%) with TX at 4( 18.9 12.89%, P 0.05) and 8 wk (16.98 11.61%, P 0.05) and significant mean reduction in post-EVH peak falls in FEF25–75 from 0w k (40.6 15.28%) with TX at 4 (33.1 17.11%, P 0.01) and 8 (29.7 17.42%, P 0.05) wk. No changes in FEV1 or FEF25–75 were observed in the PL group at any time point. Mean eNO for PL and TX groups at 0, 4, and 8 wk (46.8 31.33, 46.5 35.73, 49.3 37.12 vs 35.2 26.87, 29.1 17.26, 34.7 21.11 ppb, respectively) was not significantly different. Conclusions: UWP may augment pulmonary antioxidant capacity and be therapeutically beneficial in individuals exhibiting EIB, as postchallenge pulmonary function improved with supplementation. The lack of significant change in eNO suggests that the pulmonary function improvements from UWP supplementation are independent of eNO. Key Words: ASTHMA, INFLAMMATION, PULMONARY FUNCTION, WHEY PROTEIN, GLUTATHIONE.

The Reflection Grating Spectrometer of the Constellation-X mission has two strong candidate configurations. The first configuration, the in-plane grating (IPG), is a set of reflection gratings similar to those flown on XMM-Newton and has grooves perpendicular to the direction of incident light. In the second configuration, the off-plane grating (OPG), the grooves are closer to being parallel to the incident light, and diffract along a cone. It has advantages of higher packing density, and higher reflectivity. Confinement of these gratings to sub-apertures of the optic allow high spectral resolution. We have developed a raytrace model and analysis technique for the off-plane grating configuration. Initial estimates indicate that first order resolving powers in excess of 1000 (defined with half-energy width) are achievable for sufficiently long wavelengths (λ ≥ 12a), provided separate accommodation is made for gratings in the subaperture region farther from the zeroth order location.

Soft-tissue tumors in children (

Questionnaires on exercise practices, reasons for exercising, factors that would increase exercise, and demographics were mailed to a stratified random sample of 19,510 active duty personnel in all of the United States military services who were stationed at 38 large military installations and a number of remote locations. Responses were returned by 8,572 (55%). Approximately 63% exercised three times a week for 15-20 minutes, and 15% did not exercise at all. Mean BMI was 25.2. The top five reasons for exercising were to improve physical conditioning, have fun, manage weight, improve appearance and manage stress.

Study design Cadaveric study on the biomechanics of osteoporotic vertebral bodies augmented and not augmented with polymethylmethacrylate cement. Objectives To determine the strength and stiffness of osteoporotic vertebral bodies subjected to compression fractures and 1) not augmented, 2) augmented with unipedicular injection of cement, or 3) augmented with bipedicular injection of cement. Summary of background data Percutaneous vertebroplasty is a relatively new method of managing osteoporotic compression fractures, but it lacks biomechanical confirmation. Methods Fresh vertebral bodies (L2-L5) were harvested from 10 osteoporotic spines (T scores range, -3.7 to -8.8) and compressed in a materials testing machine to determine intact strength and stiffness. They were then repaired using a transpedicular injection of cement (unipedicular or bipedicular), or they were unaugmented and recrushed. Results Results suggest that unipedicular and bipedicular cement injection restored vertebral body stiffness to intact values, whereas unaugmented vertebral bodies were significantly more compliant than either injected or intact vertebral bodies. Vertebral bodies injected with cement (both bipedicular and unipedicular) were significantly stronger than the intact vertebral bodies, whereas unaugmented vertebral bodies were significantly weaker. There was no significant difference in loss in vertebral body height between any of the augmentation groups. Conclusions This study suggests that unipedicular and bipedicular injection of cement, as used during percutaneous vertebroplasty, increases acute strength and restores stiffness of vertebral bodies with compression fractures.

We report a case of small cell osteosarcoma arising in the distal ulna. The radiologic and pathologic features of this histologic variant of osteosarcoma that allow differentiation from other lytic lesions with small round cells are discussed.

Classic adamantinoma of the long bones is a rare, low-grade malignant neoplasm arising most often in the tibia and usually in patients during the second to fifth decades. Although adamantinomas have been described in children, the histologic pattern in this age group is different from that seen in adults and resembles osteofibrous dysplasia. The usual pattern of adamantinoma in children has been termed "differentiated adamantinoma" and follows a benign course. We report a case of adamantinoma in the proximal tibia of a 3-year-old patient. The lesion had abundant epithelial component with formation of keratin pearls, a pattern that has been described only in classic adamantinoma occurring in adults. Since differentiated adamantinomas are essentially benign and classic adamantinomas are low-grade malignancies, the finding of a classic variant at this young age raised important therapeutic and prognostic issues.

There is considerable controversy about whether cystic arthrosis is a primary or secondary phenomenon in the development of degenerative joint disease of the hip1,2,4,5,8,10,13,15,18. Proponents of the bone-contusion theory have suggested that a localized area of subchondral necrosis of bone resulting from repetitive microtrauma leads to cystic degeneration, leaving the articular cartilage intact1,2,4,8,13,18. Proponents of the synovial intrusion theory believe that traumatic defects in the articular cartilage allow intrusion of synovial fluid through subchondral microfractures, resulting in cystic degeneration5,10,15. Both groups of proponents agree that, in the later stages of degenerative osteoarthrosis of the hip, subchondral fractures, cystic collapse of the acetabulum, and diffuse degenerative changes predominate on both sides of the joint. Both groups also agree that it should be possible to slow the progression of the disease by timely and appropriate operative intervention. Often, by the time patients who have pain in the hip secondary to degenerative joint disease are seen, there are characteristic roentgenographic changes, such as decreased joint space, increased subchondral sclerosis, subchondral cysts, and osteophytosis; thus, it is impossible to determine whether the cystic changes were the precursor of the late changes. This report illustrates the evolution of degenerative joint disease of the hip. The sequence of changes supports the theory that cystic arthrosis is a primary phenomenon that may precede and hasten the onset of osteoarthrosis in some patients. A thirty-three-year-old man was involved in a motor-vehicle accident in July 1988; his automobile was struck from behind by a vehicle traveling at approximately sixty-four kilometers (forty miles) per hour. The patient had pain in the lumbosacral region and …

The overall objective of the Phase I work was to evaluate certain key technical aspects of a proposed Imaging Mass Detector. The proposed instrument consists of a time of flight fission fragment plasma desorption mass spectrometer with a novel imaging system for locating the position on the specimen from which molecules are desorbed. Mass Spectrometers which utilize fission fragments to plasma desorb molecular ions from samples have been characterized in the scientific literature and did not require further development. The unique untested principle of the proposed system was that of tracking the fission fragments and combining the mass and spatial information to develop mass images of specimens. The primary task of this Phase I program was, therefore, to identify, test, and evaluate the most suitable spatial detector technology. The main results of the investigation has been to demonstration that such a design is feasible and to provide a layout of a plausible system.