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BACKGROUND: Adjacent segment disease (ASD) above a previous posterior lumbar instrumented fusion can be managed with minimally invasive lateral lumbar interbody fusion. Earlier procedures with stand-alone lateral cages risked nonunion, and lateral cages with separate lateral plates risked lumbar plexus injury and vertebral fracture. We investigated clinical and radiographic outcomes of an expandable lateral titanium interbody cage with an integrated lateral fixation (eLLIFp) device as a stand-alone treatment for symptomatic ASD above a previous posterior lumbar fusion and performed a comparative cost analysis of eLLIFp to alternative operations for ASD. METHODS: In this prospective, observational study, patients with ASD above 1-, 2-, 3-, or 4-level instrumented posterior fusions underwent surgery with lateral expandable titanium cage(s) with an integrated lateral plate with single screws into each adjacent vertebra from August 2017 to August 2019. Multimodality intraoperative neural monitoring was performed. Patient-reported outcomes, computed tomography outcomes, and total costs were analyzed. RESULTS: A total of 33 patients received 35 eLLIFp cages. All clinical outcomes improved significantly. The eLLIFp cages added 2.2° segmental lordosis and 2.7 mm posterior disc height. Interbody fusion rate was 94% at 12 months. There were 2 neurologic complications (6%): 1 patient reported transient anterior thigh numbness and 1 had mild persistent L4 radiculopathy. No cage subsidence, cage migration, screw loosening, or vertebral fracture occurred. No revision lateral surgery, posterior decompression, or supplemental posterior fixation was required. The total eLLIFp cost (AU$19,715) was lower than the cost for all other procedures. CONCLUSIONS: eLLIFp provided a minimally invasive, low morbidity, cost-effective, and robust alternative to traditional posterior construct extension surgery for rostral lumbar ASD in selected patients with 1- to 2-level stenosis and minimal deformity. CLINICAL RELEVANCE: Traditional ASD treatment involves substantial risks and expense. eLLIFp should be considered a safe, effective, and lower cost alternative to posterior construct extension surgery. LEVEL OF EVIDENCE: 2.

Parallel Contributed Talk at the "XIX International Workshop on Neutrino Telescopes" on line - 18-26 February, 2021

The three body pion decays π+→l+νX(l=e,μ), where X is a weakly interacting neutral boson, were searched for using the full data set from the PIENU experiment. An improved limit on Γ(π+→e+νX)/Γ(π+→μ+νμ) in the mass range 0

International audience; In the present work of the PIENU experiment, heavy neutrinos were sought in pion decays \(\pi ^{ + } \to \mu ^{ + }\nu \). No evidence for extra peak was found in the muon kinetic energy spectrum and 90% confidence level upper limits were set on the neutrino mixing matrix \(|U_{\mu i}|^{2}\) in the mass range of 15.7 to 33.8 MeV/c^2, improving an order of magnitude over previous experiments. Current status of lepton universality test is also reported.

A prospective single-surgeon nonrandomized clinical study.To evaluate the radiographic and clinical outcomes, by fixation type, in extreme lateral interbody fusion (XLIF) patients and provide an algorithm for determining patients suitable for stand-alone XLIF.XLIF may be supplemented with pedicle screw fixation, however, since stabilizing structures remain intact, it is suggested that stand-alone XLIF can be used for certain indications. This eliminates the associated morbidity, though subsidence rates may be elevated, potentially minimizing the clinical benefits.A fixation algorithm was developed after evaluation of patient outcomes from the surgeon's first 30 cases. This algorithm was used prospectively for 40 subsequent patients to determine the requirement for supplemental fixation. Preoperative, postoperative, and 12-month follow-up computed tomography scans were measured for segmental and global lumbar lordosis and posterior disk height. Clinical outcome measures included back and leg pain (visual analogue scale), Oswestry Disability Index (ODI), and SF-36 physical and mental component scores (PCS and MCS).Preoperatively to 12-month follow-up there were increases in segmental lordosis (7.9-9.4 degrees, P=0.0497), lumbar lordosis (48.8-55.2 degrees, P=0.0328), and disk height (3.7-5.5 mm, P=0.0018); there were also improvements in back (58.6%) and leg pain (60.0%), ODI (44.4%), PCS (56.7%), and MCS (16.1%) for stand-alone XLIF. For instrumented XLIF, segmental lordosis (7.6-10.5 degrees, P=0.0120) and disk height (3.5-5.6 mm, P0.001) increased, while lumbar lordosis decreased (51.1-45.8 degrees, P=0.2560). Back (49.8%) and leg pain (30.8%), ODI (32.3%), PCS (37.4%), and MCS (2.0%) were all improved. Subsidence occurred in 3 (7.5%) stand-alone patients.The XLIF treatment fixation algorithm provided a clinical pathway to select suitable patients for stand-alone XLIF. These patients achieved positive clinical outcomes, satisfactory fusion rates, with sustained correction of lordosis and restoration of disk height.

In the present work of the PIENU experiment, heavy neutrinos were sought in pion decays pi(+) -> mu(+)nu at rest by examining the observed muon energy spectrum for extra peaks in addition to the expected peak for a light neutrino. No evidence for heavy neutrinos was observed. Upper limits were set on the neutrino mixing matrix vertical bar U-mu i vertical bar(2) in the neutrino mass region of 15.7-33.8 MeV/c(2), improving on previous results by an order of magnitude. (C) 2019 The Authors. Published by Elsevier B.V.

A search for massive neutrinos has been made in the decay π+→e+ν. No evidence was found for extra peaks in the positron energy spectrum indicative of pion decays involving massive neutrinos (π→e+νh). Upper limits (90% C.L.) on the neutrino mixing matrix element |Uei|2 in the neutrino mass region 60–135 MeV/c2 were set and are an order of magnitude improvement over previous results.

International audience; Power amplification and pulse compression of short-pulse laser beams by three-wave nonlinear processes in a plasma was proposed by Malkin, Shvets, and Fisch [Phys. Rev. Lett. 82, 4448 (1999)] as a potential path to exceed the limits of the highly successful technique of chirped pulse amplification [D. Strickland and G. Mourou, Opt. Commun. 56, 219 (1985)] developed three decades ago. The parametric processes considered, Raman and Brillouin scattering, are notoriously difficult to control and to predict theoretically because of the dependence on plasma properties and other nonlinear processes. Previous experiments of backward Raman and Brillouin amplifiers have fallen far short of the predictions of simulations and theory and achieved only a very small energy transfer. In this paper, laser-plasma amplification of subpicosecond pulses above the Joule level is demonstrated with a large energy transfer and a very high efficiency, up to 20%, a major milestone for this scheme to become a solution for the next generation of ultrahigh-intensity lasers. In addition, three-dimensional simulations of the amplification process quantitatively match the experimental results and demonstrate the ability of predictive simulations for the optimization of experiments. The global behavior of the amplification process is reproduced, including the evolution of the spatial profile of the amplified seed, the pulse length of the amplified seed, and the influence of parasitic spontaneous Raman and Brillouin scattering.

Study Design Retrospective analysis of prospectively collected registry data. Objective This study aimed to compare the clinical and radiologic outcomes between comparative cohorts of patients having anterior lumbar interbody fusion (ALIF) and patients having lateral lumbar interbody fusion (LLIF). Methods Ninety consecutive patients were treated by a single surgeon with either ALIF ( n = 50) or LLIF ( n = 40). Inclusion criteria were patients age 45 to 70 years with degenerative disk disease or grade 1 to 2 spondylolisthesis and single-level pathology from L1 to S1. Patient-reported outcome measures included pain (visual analog scale), disability (Oswestry Disability Index [ODI]), and quality of life (Short Form 36 physical component score [PCS] and mental component scores [MCS]). Assessment of fusion and measurement of lordosis and posterior disk height were performed on computed tomography scans. Results At 24 months, patients having ALIF had significant improvements in back (64%) and leg (65%) pain and ODI (60%), PCS (44%), and MCS (26%; p 0.05). The fusion rate was 100% for ALIF and 95% for LLIF ( p = 0.1948). ALIF added ∼6 degrees of lordosis and 3 mm of height, primarily measured at L5–S1, and LLIF added ∼3 degrees of lordosis and 2 mm of height between L1 to L5. Mean follow-up was 34.1 months. Conclusions In comparative cohorts of patients having ALIF and patients having LLIF at 24 months postoperatively, there were no significant differences in clinical outcomes, complication rates, or fusion rates.

The PIENU experiment at TRIUMF is aimed at a measurement of the branching ratio R e / μ = Γ ( ( π + → e + ν e ) + ( π + → e + ν e γ ) ) / Γ ( ( π + → μ + ν μ ) + ( π + → μ + ν μ γ ) ) with precision 0.1 % . Incident pions, delivered at the rate of 60 kHz with momentum 75 MeV/c, were degraded and stopped in a plastic scintillator target. Pions and their decay product positrons were detected with plastic scintillators and tracked with multiwire proportional chambers and silicon strip detectors. The energies of the positrons were measured in a spectrometer consisting of a large NaI(Tl) crystal surrounded by an array of pure CsI crystals. This paper provides a description of the PIENU experimental apparatus and its performance in pursuit of R e / μ .

Background and Study Aims The learning curve associated with the adoption of minimally invasive surgery techniques has limited its adoption by many traditionally open surgeons. The use of dynamic electromyography (EMG) to guide the placement of percutaneous pedicle screws (PS) can lessen the learning curve by providing real-time feedback on neural proximity relative to the screw. This study aimed to investigate the safety and accuracy of a single surgeon's experience transitioning from open pedicle screws (OS) to PS using intraoperative fluoroscopy and dynamic EMG. Materials and Methods Forty consecutive patients were treated with EMG and fluoroscopy-guided PS placement by a single surgeon and followed through a prospective registry. This was cross-referenced with a cohort of 53 consecutive patients treated with OS in 2011. Computed tomography was used to check the screw position 1 day after surgery. A misplaced pedicle screw was defined as a breach of the pedicle wall. The accuracy of PS placement in association with dynamic EMG was compared with that of OS. Results A total of 204 PS were inserted in the study cohort with 97.5% accuracy. Five (2.5%) were misplaced (three medial and two lateral). All three medial screws displayed a caution message (yellow: 8mA) on insertion. No screw caused visceral or neurologic complications postoperatively, and none required revision. In the OS cohort, 254 screws were placed with 94.9% accuracy, 13 (5.1%) were misplaced (8 medial, 3 lateral, and 2 superior), and 3 (1.2%) required revision. Conclusions Dynamic EMG combined with intraoperative fluoroscopy and advanced instrumentation provides a safe, real-time, and accurate method for PS placement.

The lateral approach for anterior interbody fusion allows placement of a large footprint intervertebral spacer to indirectly decompress the neural elements through disc height restoration and resultant soft tissue changes. However, it is not well understood under what circumstances indirect decompression in lateral approach surgery is sufficient. This report aimed to evaluate clinical scenarios where indirect decompression was and was not sufficient in symptom resolution when using lateral interbody fusion.A prospective study was undertaken of 122 consecutive patients treated with lateral interbody fusion without direct decompression. Pre- and postoperative symptomatology was assessed to evaluate the extent of neural decompression following implantation with a lateral polyetheretherketone spacer. Failure to improve or resolve preoperative radicular pain was considered a failure of indirect decompression and indicated these patients for additional posterior decompressive surgery.Unplanned second stage decompression was required in 11 patients. Of these patients, 7/11 early in this series had pathology that was underappreciated including spondylolisthesis from high grade facet arthropathy with instability (3), bony lateral recess stenosis (3) and both spondylolisthesis/stenosis (1). Three patients had iatrogenic leg pain through cage misplacement. There was one failure of indirect decompression that could not be explained through retrospective analysis of the patient's record.Indirect decompression clearly has a role in minimizing the amount of surgery that is required. However, it is important to consider the circumstances where this technique may be effective and preoperative considerations that may improve patient selection.

Object The use of recombinant human bone morphogenetic protein–2 (rhBMP-2) in anterior lumbar interbody fusion (ALIF) is controversial regarding the reported complication rates and cost. The authors aimed to assess the complication rates of performing ALIF using rhBMP-2. Methods This is a prospective study of consecutive patients who underwent ALIF performed by a single spine surgeon and a single vascular surgeon between 2009 and 2012. All patients underwent placement of a polyetheretherketone (PEEK) cage filled with rhBMP-2 and a separate anterior titanium plate. Preoperative clinical data, operative details, postoperative complications, and clinical and radiographic outcomes were recorded for all patients. Clinical outcome measures included back and leg pain visual analog scale scores, Oswestry Disability Index (ODI), and SF-36 Physical and Mental Component Summary (PCS and MCS) scores. Radiographic assessment of fusion was performed using high-definition CT scanning. Male patients were screened pre- and postoperatively regarding sexual dysfunction, specifically retrograde ejaculation (RE). Results The study comprised 131 patients with a mean age of 45.3 years. There were 67 men (51.1%) and 64 women (48.9%). Of the 131 patients, 117 (89.3%) underwent ALIF at L5–S1, 9 (6.9%) at L4–5, and 5 (3.8%) at both L4–5 and L5–S1. The overall complication rate was 19.1% (25 of 131), with 17 patients (13.0%) experiencing minor complications and 8 (6.1%) experiencing major complications. The mean estimated blood loss per ALIF level was 115 ml. There was 1 incidence (1.5%) of RE. No significant vascular injuries occurred. No prosthesis failure occurred with the PEEK cage and separate anterior screw-plate. Back and leg pain improved 57.2% and 61.8%, respectively. The ODI improved 54.3%, with PCS and MCS scores improving 41.7% and 21.3%, respectively. Solid interbody fusion was observed in 96.9% of patients at 12 months. Conclusions Anterior lumbar interbody fusion with a vascular access surgeon and spine surgeon, using a separate cage and anterior screw-plate, provides a very robust and reliable construct with low complication rates, high fusion rates, and positive clinical outcomes, and it is cost-effective. The authors did not experience the high rates of RE reported by other authors using rhBMP-2.

The PIENU experiment at TRIUMF aims to measure the branching ratio of the pion decay modes $R^{\pi}=[{\pi}^+{\rightarrow}e^+{\nu}_e({\gamma})]/[{\pi}^+{\rightarrow}{\mu}^+{\nu}_{\mu}({\gamma})]$ with precision of $

The collimation of astrophysically-relevant plasma ejecta in the form of narrow jets via a poloidal magnetic field is studied experimentally by irradiating a target situated in a 20 T axial magnetic field with a 40 J, 0.6 ns, 0.7 mm diameter, high-power laser. The dynamics of the plasma shaping by the magnetic field are studied over 70 ns and up to 20 mm from the source by diagnosing the electron density, temperature and optical self-emission. These show that the initial expansion of the plasma is highly magnetized, which leads to the formation of a cavity structure when the kinetic plasma pressure compresses the magnetic field, resulting in an oblique shock [A. Ciardi et al., Phys. Rev. Lett. 110, 025002 (2013)]. The resulting poloidal magnetic nozzle collimates the plasma into a narrow jet [B. Albertazzi et al., Science 346, 325 (2014)]. At distances far from the target, the jet is only marginally magnetized and maintains a high aspect ratio due to its high Mach-number (M∼20) and not due to external magnetic pressure. The formation of the jet is evaluated over a range of laser intensities (1012–1013 W/cm2), target materials and orientations of the magnetic field. Plasma cavity formation is observed in all cases and the viability of long-range jet formation is found to be dependent on the orientation of the magnetic field.

The pion branching ratio, $R_{\pi } = \frac { {\Gamma }(\pi ^{+} \rightarrow e^{+} \nu _{e} + \pi ^{+}\rightarrow e^{+} \nu _{e} \gamma )}{\Gamma (\pi ^{+} \rightarrow \mu ^{+} \nu _{\mu } + \pi ^{+} \rightarrow \mu ^{+} \nu _{\mu } \gamma )}$ , provides a sensitive test of lepton universality and constraints on many new physics scenarios. The theoretical uncertainty on the Standard Model prediction of R π is 0.02 %, a factor of twenty smaller than the experimental uncertainty. The analysis of a subset of data taken by the PIENU experiment will be presented. The result, R π = (1.2344 ± 0.0023(s t a t) ± 0.0019(s y s t)) ⋅ 10−4 [1], is consistent with the Standard Model prediction and represents a 0.1 % constraint on lepton non-universality.

STUDY DESIGN Retrospective analysis of prospectively collected, nonrandomized radiographical data. OBJECTIVE To examine the relationship between the presence of preoperative metabolically active facet arthropathy (FA) and the amount of indirect foraminal decompression gained after extreme lateral interbody fusion (XLIF). SUMMARY OF BACKGROUND DATA Although evidence of significant radiographical indirect decompression after XLIF has been shown, the relationship between the extent of indirect decompression and the presence of potentially attenuating, FA is yet to be studied. METHODS A prospective database of consecutive patients undergoing XLIF was retrospectively analyzed. Posterior disc height, foraminal height, and cross-sectional foraminal area were measured on computed tomographic scans obtained preoperatively and 2 days postoperatively. The selected radiographical parameters were examined with respect to the presence of FA based on preoperative computed tomographic and bone scans. RESULTS Fifty-two consecutive patients underwent 79 levels of XLIF without direct decompression. Average age was 66.4 years and 34 (65.4%) were females. Surgery resulted in significant increases in posterior disc height 3.0 to 5.7 mm (89.0% increase), P

The PIENU experiment aims to measure the branching ratio of the charged pion decay with precision of < 0.1 %. This measurement is much sensitive to search for massive neutrinos coupled to electrons in ${\pi }^{+}{\rightarrow }e^{+}{\nu }_{e}$ decay. The initial analysis was completed and the upper limit on the neutrino mixing parameter |U e i |2 in the neutrino mass range of 0 to 55 MeV/c 2 was improved by a factor of 1.5, and the sensitivity for the mass range of 68 to 129 MeV/c 2 was improve by a factor of up to 4.

Emergency departments must have appropriate resources and equipment available to meet the unique needs of children. We assessed the availability of stakeholder-endorsed quality structure performance measures for pediatric emergency department patients.A survey of Child Health Corporation of America member hospitals was conducted. Six broad equipment groups were queried: general, monitoring, respiratory, vascular access, fracture-management, and specialized pediatric trays. Equipment availability was determined at the level of the individual item, 6 broad groups, and 44 equipment subgroups. The survey queried the availability of 8 protocol/procedure elements: method to identify age-based abnormal vital signs, patient-centered care advisory council, bronchiolitis evidence-based guideline, pediatric radiation dosing standards, suspected child abuse protocols, use of validated pediatric triage tool, and presence of nurse and physician pediatric coordinators.Fifty-two percent (22/42) of sites completed the survey. Forty-one percent reported availability of all 113 recommended equipment items. Every hospital reported complete availability of equipment in 77% of the subgroups. The most common missing items were adult-sized lumbar puncture needles, hypothermia thermometers, and various sizes of laryngeal mask airways. Regarding the protocol/procedure elements, a method to identify age-based abnormal vital signs, pediatric radiation dosing standard, and nurse and physician pediatric coordinators were present in 100%. Ninety-five percent used a validated triage tool and had suspected child abuse protocols.Presence of necessary pediatric emergency equipment is better in the surveyed hospitals than in prior reports. Most responding hospitals have important protocol/procedures in place. These data may provide benchmarks for optimal care.

Study Design. A retrospective cohort study. Objective. The aim of this study was to determine the fusion rate using recombinant human bone morphogenetic protein (rhBMP) in spinal surgery and to estimate the risk of cancer subsequent to their use. Summary of Background Data. rhBMP may obviate the need for iliac crest bone graft harvest and provides similar or higher fusion rates than autologous bone graft. Recently, there are concerns that rhBMPs may either cause cancer or accelerate progression. Methods. Patients were treated by 2 spine surgeons between 2002 and 2012. Inclusion criteria were patients who resided in the state of Victoria, Australia, undergoing lumbar fusion (anterior, lateral, posterior, and posterolateral) with rhBMP [either rhBMP-2 (Infuse) or rhBMP-7 (OP-1)]. Exclusion criteria were patients who reported having an invasive cancer diagnosis before the spinal fusion procedure. The occurrence of incident cancers was obtained from record linkage to the Victorian Cancer Registry. Results. A total of 527 patients were included in the cohort, with a mean follow-up of 4.4 years (1.8–11.5). Patients received Infuse in 77% of cases and OP-1 in 23%. The mean Infuse does was 10.2 mg (2.5–48.0) and 3.3 mg (1.7–6.6) for OP-1. There was no significant difference in fusion rates between Infuse (90.1%) and OP-1 (91.9%) (P = 0.42). The overall success of interbody fusion with rhBMP was 93.5% at 12 months. Twenty-seven patients were diagnosed with an invasive cancer since treatment (20 Infuse and 7 OP-1 patients). Comparing the observed numbers in our study cohort with those expected on the basis of the Victorian population's age and sex-specific rates, we observed that the study cohort was not at a significantly increased risk of cancer. The standardized incidence ratio for cancer overall (of any type) was 0.84 [95% confidence interval (95% CI) 0.56–1.21]. Conclusion. Off-label use of rhBMP provided high fusion rates with no evidence of a significantly increased risk of cancer. Conclusion. Level of Evidence: 4

Using a narrow band positron beam, the response of a large high-resolution NaI(Tl) crystal to an incident positron beam was measured. It was found that nuclear interactions cause the appearance of additional peaks in the low energy tail of the deposited energy spectrum.

An extension of the TRIUMF M13 low-energy pion channel designed to suppress positrons based on an energy-loss technique is described. A source of beam channel momentum calibration from the decay pi+ --> e+ nu is also described., 5 pages

A new measurement of the branching ratio R_{e/μ}=Γ(π^{+}→e^{+}ν+π^{+}→e^{+}νγ)/Γ(π^{+}→μ^{+}ν+π^{+}→μ^{+}νγ) resulted in R_{e/μ}^{exp}=[1.2344±0.0023(stat)±0.0019(syst)]×10^{-4}. This is in agreement with the standard model prediction and improves the test of electron-muon universality to the level of 0.1%.

OBJECT Intervertebral cage settling during bone remodeling after lumbar lateral interbody fusion (LIF) is a common occurrence during the normal healing process. Progression of this settling with endplate collapse is defined as subsidence. The purposes of this study were to 1) assess the rate of subsidence after minimally invasive (MIS) LIF by CT, 2) distinguish between early cage subsidence (ECS) and delayed cage subsidence (DCS), 3) propose a descriptive method for classifying the types of subsidence, and 4) discuss techniques for mitigating the risk of subsidence after MIS LIF. METHODS A total of 128 consecutive patients (with 178 treated levels in total) underwent MIS LIF performed by a single surgeon. The subsidence was deemed to be ECS if it was evident on postoperative Day 2 CT images and was therefore the result of an intraoperative vertebral endplate injury and deemed DCS if it was detected on subsequent CT scans (≥ 6 months postoperatively). Endplate breaches were categorized as caudal (superior endplate) and/or cranial (inferior endplate), and as ipsilateral, contralateral, or bilateral with respect to the side of cage insertion. Subsidence seen in CT images (radiographic subsidence) was measured from the vertebral endplate to the caudal or cranial margin of the cage (in millimeters). Patient-reported outcome measures included visual analog scale, Oswestry Disability Index, and 36-Item Short Form Health Survey physical and mental component summary scores. RESULTS Four patients had ECS in a total of 4 levels. The radiographic subsidence (DCS) rates were 10% (13 of 128 patients) and 8% (14 of 178 levels), with 3% of patients (4 of 128) exhibiting clinical subsidence. In the DCS levels, 3 types of subsidence were evident on coronal and sagittal CT scans: Type 1, caudal contralateral, in 14% (2 of 14), Type 2, caudal bilateral with anterior cage tilt, in 64% (9 of 14), and Type 3, both endplates bilaterally, in 21% (3 of 14). The mean subsidence in the DCS levels was 3.2 mm. There was no significant difference between the numbers of patients in the subsidence (DCS) and no-subsidence groups who received clinical benefit from the surgical procedure, based on the minimum clinically important difference (p > 0.05). There was a significant difference between the fusion rates at 6 months (p = 0.0195); however, by 12 months, the difference was not significant (p = 0.2049). CONCLUSIONS The authors distinguished between ECS and DCS. Radiographic subsidence (DCS) was categorized using descriptors for the location and severity of the subsidence. Neither interbody fusion rates nor clinical outcomes were affected by radiographic subsidence. To protect patients from subsidence after MIS LIF, the surgeon needs to take care with the caudal endplate during cage insertion. If a caudal bilateral (Type 2) endplate breach is detected, supplemental posterior fixation to arrest progression and facilitate fusion is recommended.

A new measurement of the branching ratio R_{e/μ}=Γ(π^{+}→e^{+}ν+π^{+}→e^{+}νγ)/Γ(π^{+}→μ^{+}ν+π^{+}→μ^{+}νγ) resulted in R_{e/μ}^{exp}=[1.2344±0.0023(stat)±0.0019(syst)]×10^{-4}. This is in agreement with the standard model prediction and improves the test of electron-muon universality to the level of 0.1%.

The PIENU experiment at TRIUMF aims to measure the branching ratio of pion decays R = Γ(π(+) → e(+)ν(e) + π(+) → e(+) ν(e)γ)/Γ(π(+)→μ(+)ν(μ) + π(+) → μ(+)ν(μ)γ) with precision

A new result for the transverse mu^+ polarization, P_T, in the decay K^+ --> pi^0 mu^+ nu has been obtained in the KEK E246 experiment. Combined with our earlier result, P_T = (-1.12 +- 2.17(stat) +- 0.90(syst))x10^{-3} and Im(\xi) = (-0.28 +- 0.69(stat) +- 0.30(syst))x10^{-2}, which are consistent with no T-violation., Comment: 5 pages, 2 figures, to be published in the Proceedings of the PANIC02, Osaka, Sept 30 - Oct 4, 2002

The use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in anterior lumbar interbody fusion (ALIF) is controversial regarding the reported complication rates and cost. The authors aimed to assess the complication rates of performing ALIF using rhBMP-2.This is a prospective study of consecutive patients who underwent ALIF performed by a single spine surgeon and a single vascular surgeon between 2009 and 2012. All patients underwent placement of a polyetheretherketone (PEEK) cage filled with rhBMP-2 and a separate anterior titanium plate. Preoperative clinical data, operative details, postoperative complications, and clinical and radiographic outcomes were recorded for all patients. Clinical outcome measures included back and leg pain visual analog scale scores, Oswestry Disability Index (ODI), and SF-36 Physical and Mental Component Summary (PCS and MCS) scores. Radiographic assessment of fusion was performed using high-definition CT scanning. Male patients were screened pre- and postoperatively regarding sexual dysfunction, specifically retrograde ejaculation (RE).The study comprised 131 patients with a mean age of 45.3 years. There were 67 men (51.1%) and 64 women (48.9%). Of the 131 patients, 117 (89.3%) underwent ALIF at L5-S1, 9 (6.9%) at L4-5, and 5 (3.8%) at both L4-5 and L5-S1. The overall complication rate was 19.1% (25 of 131), with 17 patients (13.0%) experiencing minor complications and 8 (6.1%) experiencing major complications. The mean estimated blood loss per ALIF level was 115 ml. There was 1 incidence (1.5%) of RE. No significant vascular injuries occurred. No prosthesis failure occurred with the PEEK cage and separate anterior screw-plate. Back and leg pain improved 57.2% and 61.8%, respectively. The ODI improved 54.3%, with PCS and MCS scores improving 41.7% and 21.3%, respectively. Solid interbody fusion was observed in 96.9% of patients at 12 months.Anterior lumbar interbody fusion with a vascular access surgeon and spine surgeon, using a separate cage and anterior screw-plate, provides a very robust and reliable construct with low complication rates, high fusion rates, and positive clinical outcomes, and it is cost-effective. The authors did not experience the high rates of RE reported by other authors using rhBMP-2.

The branching ratio, Re/μ = Γ(π → eν + eνγ)/Γ(π → μν + μνγ), provides a sensitive test of muon-electron universality in weak interactions. The status of the PIENU experiment at TRIUMF, which aims to improve the precision of the Re/μ measurement by a factor of > 5, is presented.

A device has been developed with moveable liquid nitrogen and liquid helium volumes that is capable of reaching over two meters into the coldest regions of a cryostat or dilution refrigerator and reliably extracting or installing a target of solid, polarized hydrogen deuteride (HD). This Transfer Cryostat incorporates a cylindrical neodymium rare-earth magnet that is configured as a Halbach dipole, which is maintained at 77 K and produces a 0.1 T field around the HD target. Multiple layers provide a hermetic 77 K-shield as the device is used to maintain a target at 2 K during a transfer between cryostats. Tests with frozen-spin HD show negligible polarization loss for either H or D over typical transfer periods. Multiple target transfers with this apparatus have shown an overall reliability of about 95% per transfer, which is a significant improvement over earlier versions of the device.

The ratio of the $K^{+}\to \pi^{0} \mu^{+} \nu$ ($K_{\mu3}^+$) and $K^{+}\to \pi^{0} e^{+} \nu$ ($K_{e3}^+$) decay widths, $\Gamma(K_{\mu 3})/\Gamma(K_{e3})$, has been measured with stopped positive kaons. $K_{\mu3}^+$ and $K_{e3}^+$ samples containing 2.4$\times 10^4$ and 4.0$\times 10^4$ events, respectively, were analyzed. The $\Gamma(K_{\mu3})/\Gamma(K_{e3})$ ratio was obtained to be 0.671$\pm$0.007(stat.)$\pm$0.008(syst.) calculating the detector acceptance by a Monte Carlo simulation with the assumption of $\mu$-$e$ universality in $K_{l3}^+$ decay. The coefficient of the $q^2$ dependent term of the $f_0$ form factor was also determined to be $\lambda_0$=0.022$\pm$0.005(stat.)$\pm$0.004(syst.).

The T violating parameter, i(xi), of the decay K+ --> pi(0)mu(+)upsilon, has been determined in KEK experiment E246 from a measurement of the transverse mu(+) polarization, PT. The experiment is the first to use stopped K+ which allows a null test, formation of a double ratio for PT, and enhances the ratio i(xi)/P-T. The results from the 1996-1997 data are: i(xi) = -0.013 +/- 0.016 +/- 0.003 similar to 3P(T). The first error, due to statistics, dominates over the second which is due to systematics. Considerably more data taken in 1998 is under analysis and additional running time has been approved by KEK.

An improved search for a $T$-violating transverse muon polarization $({P}_{T})$ in ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\mu}}^{+}\ensuremath{\nu}$ decay was performed using kaon decays at rest. By means of this method, ${P}_{T}$ was extracted with small systematic errors, ${P}_{T}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.0042\ifmmode\pm\else\textpm\fi{}0.0049(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.0009(\mathrm{syst})$, and the $T$-violation parameter was determined to be $\mathrm{Im}\ensuremath{\xi}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.013\ifmmode\pm\else\textpm\fi{}0.016(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.003(\mathrm{syst})$.

The photon spectra from radiative muon capture (RMC) on O, Al, Si, Ti, Zr, and Ag have been measured for photon energies greater than 57 MeV using a cylindrical pair spectrometer at the TRIUMF cyclotron. Values of ${R}_{\ensuremath{\gamma}},$ the ratio of the radiative rate for photon energies above 57 MeV, to the nonradiative rate, are $1.67\ifmmode\pm\else\textpm\fi{}0.18,$ $1.40\ifmmode\pm\else\textpm\fi{}0.11,$ $2.09\ifmmode\pm\else\textpm\fi{}0.20,$ $1.30\ifmmode\pm\else\textpm\fi{}0.12,$ $1.31\ifmmode\pm\else\textpm\fi{}0.15$, and $1.12\ifmmode\pm\else\textpm\fi{}0.13$, respectively, in units of ${10}^{\ensuremath{-}5}$. The Al/Si rate difference confirms an earlier result. The Ti/Ca rate difference and the rate suppression in Zr and Ag are new results which confirm that the RMC rate is a much smoother function of neutron excess than of atomic number. This suggests that Pauli blocking is relatively more important for radiative capture than for nonradiative capture. The value of the ratio of the induced weak pseudoscalar to axial coupling constants, ${g}_{p}{/g}_{a},$ for O was found to be $4.9\ifmmode\pm\else\textpm\fi{}0.6,$ $6.3\ifmmode\pm\else\textpm\fi{}1.1$, or ${8.1}_{\ensuremath{-}2.1}^{+1.8}$, depending on the theory used to extract it. These values are in good or fair agreement with the partially conserved axial-vector current (PCAC) hypothesis. For the other nuclei studied, large model dependences or a lack of detailed RMC calculations made tests of the PCAC hypothesis difficult.

New high-precision measurements of p( γ , π) and p( γ , γ) cross sections and beam asymmetries have been combined with other polarization ratios in a simultaneous analysis of both reactions. Compton scattering has provided two important new constraints on the photo-pion amplitude. The E2/M1 mixing ratio for the N → Δ transition extracted from this analysis is EMR = -3.0% ± 0.3 (stat + sys) ± 0.2 (model).

A pure weak interaction such as muon decay μ → ev \(\overline{v}\) is characterized by a V-A amplitude. When hadrons participate the strong force induces additional couplings and the reaction is classified as semi-leptonic. These additional couplings are real due to time reversal invariance. The scalar and tensor couplings are expected to vanish because these currents have the wrong G-parity and experimentally non-zero values have not been found. In beta decay n → pe \(\overline{v}\) the renormalized axial vector strength, g a , and the weak magnetism strength, g m , which is predicted by CVC, are accurately measured.

A TRIUMF experiment, PIENU, which aims to measure the branching ratio of pion decays, R = Γ(π→eν+eνγ)/Γ(π→μν+μνγ) to a precision of 0.1% or better is described. Such a measurement provides the best test of electron-muon universality in weak interactions and is sensitive to an effective mass scale of up to 1000 TeV in new physics.

A gas recycling system to prevent losses of isotopically enriched hydrogen gas has been developed for the operation of a liquid target (2.7 l) used by the Radiative Muon Capture group at TRIUMF. The experimental requirements for high gas purity (chemical impurities below 10 −9 ), low operating pressure (below 1 bar abs) and high loading pressure (about 10 bar needed for a palladium purifier) together with the usual hydrogen safety requirements were satisfied with a metal hydride storage device in combination with a small pump/compressor system. A description of the complete system together with its characteristic operational data are given in this paper.

Compton backscattering gamma ray beams are characterized by a high degree of linear and circular polarization with low unpolarized backgrounds and have proven to provide very precise measurements of polarization observables. Latest results from LEGS and GRAAL experiments on proton and deuteron targets are presented. The Σ beam asymmetry for ω photoproduction has been measured by the GRAAL collaboration for both the ω→π0γ and the ω→π+π−π0 decay channels on the proton target; single and double polarization asymmetries have been provided also for the K photoproduction channel. E and G double polarization asymmetries for single pion photoproduction on the proton and deuteron have been measured at LEGS using a frozen spin HD target.

The branching ratio of pion decays, R = Γ(π+→e+νe+π+→e+νeγ)Γ(π+→μ+νμ+π+→μ+νμγ is one of the most accurately calculated decay processes involving hadrons and has provided one of the most stringent tests of the hypothesis of electron-muon universality in weak interactions. The current experimental branching ratio Rexp = (1.230±0.004)×10−4 is 40 times less precise than the theoretical prediction RSM = 1.2352(1)10−4. The TRIUMF PIENU experiment aims at measuring the pion branching ratio with a precision improved by at least a factor five.

Evidence of massive neutrinos in the π+→e+ν decay spectrum was sought with the background π+→μ+→e+ decay chain highly suppressed. Upper limits (90% C.L.) on the neutrino mixing matrix element |Uei|2 in the neutrino mass region 60-129 MeV/c2 were set at the level of 10−8.

The positron spectrum from the decay ..pi../sup +/..-->..e/sup +/..nu../sub e/ has been examined for evidence of peaks arising from an admixture in the ..nu../sub e/ weak eigenstate of massive neutrinos. Limits on the intensity of such peaks, together with the measured ..pi -->..e..nu.. branching ratio, have been used to derive constraints on the neutrino mixing parameters over the range 4 MeV

Results from three independent measurements of the {ital p}({rvec {gamma}},{pi}{sup 0}) reaction are presented for incident photon energies between 243 and 314 MeV, and for c.m. angles of 105{degree}, 122{degree}, and 150{degree}. The ratio of cross sections measured with orthogonal states of linear polarization is sensitive to the {ital E}2 excitation of the {Delta} resonace. Comparisons are made to the predictions of various models, all of which fail to reproduce these data.