Experimental Investigation of a Long Range M = 0.95 Advanced Technology Transport Design with Four Wing-Mounted Engines

No abstract availabl

Posterior surgical approach procedures for cervical myelopathy

This is the protocol for a review and there is no abstract. The objectives are as follows: The main objective of this review is to assess the effects of laminectomy and fusion versus laminoplasty for multilevel cervical stenosis with myelopathy, on treatment outcomes such as pain, quality of life, functional and neurological improvement, and complication rates. © 2015 The Cochrane Collaboration

Trends and Costs of External Electrical Bone Stimulators and Grafting Materials in Anterior Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective review. PURPOSE: To identify the trends in stimulator use, pair those trends with various grafting materials, and determine the influence of stimulators on the risk of revision surgery. OVERVIEW OF LITERATURE: A large number of studies has reported beneficial effects of electromagnetic energy in healing long bone fractures. However, there are few clinical studies regarding the use of electrical stimulators in spinal fusion. METHODS: We used insurance billing codes to identify patients with lumbar disc degeneration who underwent anterior lumbar interbody fusion (ALIF). Comparisons between patients who did and did not receive electrical stimulators following surgery were performed using logistic regression analysis, chi-square test, and odds ratio (OR) analysis. RESULTS: Approximately 19% of the patients (495/2,613) received external stimulators following ALIF surgery. There was a slight increase in stimulator use from 2008 to 2014 (multi-level R2=0.08, single-level R2=0.05). Patients who underwent multi-level procedures were more likely to receive stimulators than patients who underwent single-level procedures (p0.05), except those in the multilevel ALIF+PLF cohort, wherein the patients who underwent stimulation had higher rates of revision surgery. CONCLUSIONS: Concurrent PLF or multi-level procedures increased patients\u27 likelihood of receiving stimulators, however, the presence of comorbidities did not. Patients who received BMA plus autograft or allograft were more likely to receive stimulation. Patients with and without bone stimulators had similar rates of revision surgery

Expression of CD44 molecules and CD44 ligands during human thymic fetal development: expression of CD44 isoforms is developmentally regulated

It has recently been recognized that CD44 comprises a large family of alternatively spliced forms.In the thymus, CD44 has been postulated to play an important role in immature T cell migration and maturation. In this paper, we have studied the expression of CD44 molecules and two CD44 ligands, hyaluronan (HA) and fibronectin (FN), during human thymic fetal development. We found that mAbs against all CD44 isoforms (A3D8 or A1G3) reacted with both thymic epithelial (TE) cells and thymocytes beginning at the time of initial colonization of the human thymus by hematopoietic stem cells at 8.2 weeks of fetal gestation. However, mAbs specific for splice variants of CD44 containing membrane-proximal inserts (11.24, 11.10 and 11.9) reacted only with terminally differentiated TE cells in and around Hassall's bodies beginning at 16-19 weeks of fetal gestation. Studies of differentiated versus undifferentiated TE cells in vitro confirmed the selective expression of CD44 variant isoforms on terminally differentiated TE cells. Expression of HA and FN was determined by fluorescence microscopy using either biotlnylated-HA binding protein or an anti-FN mAb. We found that whereas FN was present throughout the human fetal thymus beginning at 8.2 weeks, HA was not present until 16 weeks of gestational age. These data demonstrate the differential expression of standard versus variant CD44 isoforms during thymic ontogeny and implicate CD44 interactions with ligands other than HA as important in the earlier stages of humanthymus developmen

The Impact of Epidural Steroid Injections on the Outcomes of Patients Treated for Lumbar Disc Herniation: A Subgroup Analysis of the SPORT Trial.

BACKGROUND: The Spine Patient Outcomes Research Trial (SPORT) is a prospective, multicenter study of operative versus nonoperative treatment of lumbar intervertebral disc herniation. It has been suggested that epidural steroid injections may help improve patient outcomes and lower the rate of crossover to surgical treatment. METHODS: One hundred and fifty-four patients included in the intervertebral disc herniation arm of the SPORT who had received an epidural steroid injection during the first three months of the study and no injection prior to the study (the ESI group) were compared with 453 patients who had not received an injection during the first three months of the study or prior to the study (the No-ESI group). RESULTS: There was a significant difference in the preference for surgery between groups (19% in the ESI group compared with 56% in the No-ESI group, p \u3c 0.001). There was no difference in primary or secondary outcome measures at four years between the groups. A higher percentage of patients changed from surgical to nonsurgical treatment in the ESI group (41% versus 12% in the No-ESI, p \u3c 0.001). CONCLUSIONS: Patients with lumbar disc herniation treated with epidural steroid injection had no improvement in short or long-term outcomes compared with patients who were not treated with epidural steroid injection. There was a higher prevalence of crossover to nonsurgical treatment among surgically assigned ESI-group patients, although this was confounded by the increased baseline desire to avoid surgery among patients in the ESI group. Given these data, we concluded that more studies are necessary to establish the value of epidural steroid injection for symptomatic lumbar intervertebral disc herniation. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence

The effect of iliac crest autograft on the outcome of fusion in the setting of degenerative spondylolisthesis: a subgroup analysis of the Spine Patient Outcomes Research Trial (SPORT).

BACKGROUND: There is considerable controversy about the long-term morbidity associated with the use of posterior autologous iliac crest bone graft for lumbar spine fusion procedures compared with the use of bone-graft substitutes. The hypothesis of this study was that there is no long-term difference in outcome for patients who had posterior lumbar fusion with or without iliac crest autograft. METHODS: The study population includes patients enrolled in the degenerative spondylolisthesis cohort of the Spine Patient Outcomes Research Trial who underwent lumbar spinal fusion. Patients were divided according to whether they had or had not received posterior autologous iliac crest bone graft. RESULTS: There were 108 patients who had fusion with iliac crest autograft and 246 who had fusion without iliac crest autograft. There were no baseline differences between groups in demographic characteristics, comorbidities, or baseline clinical scores. At baseline, the group that received iliac crest bone graft had an increased percentage of patients who had multilevel fusions (32% versus 21%; p=0.033) and L5-S1 surgery (37% versus 26%; p=0.031) compared with the group without iliac crest autograft. Operative time was higher in the iliac crest bone-graft group (233.4 versus 200.9 minutes; p CONCLUSIONS: The outcome scores associated with the use of posterior iliac crest bone graft for lumbar spinal fusion were not significantly lower than those after fusion without iliac crest autograft. Conversely, iliac crest bone-grafting was not associated with an increase in the complication rates or rates of reoperation. On the basis of these results, surgeons may choose to use iliac crest bone graft on a case-by-case basis for lumbar spinal fusion

Radiographic Results of Expandable Interbody Devices

Introduction: Minimally invasive surgery for transforaminal lumbar interbody fusion (MIS-TLIF) has become a mainstay procedure in the treatment of degenerative conditions of the lumbar spine. Expandable interbody devices have gained popularity in recent times due to several well-cited advantages including greater correction of disc height and lordosis and decreased intraoperative disruption of neurologic structures. However, the clinical benefits offered by these devices compared to traditional static implants remain unclear. This study seeks to investigate differences in the radiographic and clinical outcomes between traditional static versus expandable interbody devices used in MIS-TLIF. Methods: Patients who underwent MIS-TLIF performed by three surgeons from 2014 to 2020 at a single institution high-volume center were retrospectively reviewed. Radiographic measurements were performed on lateral radiographs taken preoperatively, 3-weeks following, and at least 6 months following the date of surgery. Radiographic analysis included anterior and posterior disc height, segmental lordosis, endplate violation, and cage subsidence. Clinical outcomes were evaluated by assessing for the presence of radicular leg pain on the side of the TLIF following surgery at 3 months follow up. Statistical analysis included independent t tests for continuous variables and chi-square analysis for categorical values. Results: Three-hundred and sixty-seven patients who underwent MIS-TLIF for degenerative diagnoses using either a static (229 patients) or expandable (138 patients) cage were included. The mean age was 62.9 ± 11.7 years in the static group and 67.4 ± 11.2 years in the expandable group. The mean body mass index (BMI) was 30.4 ± 6.4 in the static group and 30.73 ± 7.3 in the expandable group. Patients receiving expandable cages had significantly greater anterior disc height (11.5 mm static vs. 13.2 mm expandable, p \u3c 0.001), posterior disc height (7.18 mm static vs 8.19 mm expandable, p \u3c 0.001), and segmental lordosis (6.47 degrees static vs 7.49 degrees expandable, p = 0.001) at most recent follow up. No significant differences in cage subsidence rates were noted between static (19.7%) and expandable (22.9%) devices (OR =0.823, CI 0.513 – 1.321, p = 0.42). Patients who received expandable devices reported greater improvements in leg pain at 3 months follow up (p = 0.012). Discussion: Patients who underwent MIS-TLIF with an expandable device demonstrated greater correction of anterior and posterior disc height, as well as greater and more sustained correction of segmental lordosis compared to static cages. No significant differences were noted in cage subsidence rate between static and expandable cages. Patients who received expandable devices were noted to have greater improvements in radicular leg pain

Coherent States of the SU(N) groups

Coherent states $(CS)$ of the $SU(N)$ groups are constructed explicitly and their properties are investigated. They represent a nontrivial generalization of the spining $CS$ of the $SU(2)$ group. The $CS$ are parametrized by the points of the coset space, which is, in that particular case, the projective space $CP^{N-1}$ and plays the role of the phase space of a corresponding classical mechanics. The $CS$ possess of a minimum uncertainty, they minimize an invariant dispersion of the quadratic Casimir operator. The classical limit is ivestigated in terms of symbols of operators. The role of the Planck constant playes $h=P^{-1}$, where $P$ is the signature of the representation. The classical limit of the so called star commutator generates the Poisson bracket in the $CP^{N-1}$ phase space. The logarithm of the modulus of the $CS$ overlapping, being interpreted as a symmetric in the space, gives the Fubini-Study metric in $CP^{N-1}$. The $CS$ constructed are useful for the quasi-classical analysis of the quantum equations of the $SU(N)$ gauge symmetric theories.Comment: 19pg, IFUSP/P-974 March/199

Reliable, Economic, Efficient CO2 Heat Pump Water Heater for North America

Adoption of heat pump water heating technology for commercial hot water could save up to 0.4 quads of energy and 5 million metric tons of CO2 production annually in North America, but industry perception is that this technology does not offer adequate performance or reliability and comes at too high of a cost. Development and demonstration of a CO2 heat pump water heater is proposed to reduce these barriers to adoption. Three major themes are addressed: market analysis to understand barriers to adoption, use of advanced reliability models to design optimum qualification test plans, and field testing of two phases of water heater prototypes. Market experts claim that beyond good performance, market adoption requires 'drop and forget' system reliability and a six month payback of first costs. Performance, reliability and cost targets are determined and reliability models are developed to evaluate the minimum testing required to meet reliability targets. Three phase 1 prototypes are designed and installed in the field. Based on results from these trials a product specification is developed and a second phase of five field trial units are built and installed. These eight units accumulate 11 unit-years of service including 15,650 hours and 25,242 cycles of compressor operation. Performance targets can be met. An availability of 60% is achieved and the capability to achieve >90% is demonstrated, but overall reliability is below target, with an average of 3.6 failures/unit-year on the phase 2 demonstration. Most reliability issues are shown to be common to new HVAC products, giving high confidence in mature product reliability, but the need for further work to minimize leaks and ensure reliability of the electronic expansion valve is clear. First cost is projected to be above target, leading to an expectation of 8-24 month payback when substituted for an electric water heater. Despite not meeting all targets, arguments are made that an industry leader could sufficiently develop this technology to impact the water heater market in the near term

Association of Accelerometry-Measured Physical Activity and Cardiovascular Events in Mobility-Limited Older Adults: The LIFE (Lifestyle Interventions and Independence for Elders) Study.

BACKGROUND:Data are sparse regarding the value of physical activity (PA) surveillance among older adults-particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study. METHODS AND RESULTS:Cardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home-based activity data were collected by hip-worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84-0.96; P=0.001). At baseline, every 30 minutes spent performing activities ≥500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65-0.89 [P=0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow-up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85-0.96 [P=0.001]) and duration of activity ≥500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63-0.90 [P=0.002]) were significantly associated with lower cardiovascular event rates. CONCLUSIONS:Objective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500