Discovery and insights from DSX mission's high-power VLF wave transmission experiments in the radiation belts.

Space weather phenomena can threaten space technologies. A hazard among these is the population of relativistic electrons in the Van Allen radiation belts. To reduce the threat, artificial processes can be introduced by transmitting very-low-frequency (VLF) waves into the belts. The resulting wave-particle interactions may deplete these harmful electrons. However, when transmitting VLF waves in space plasma, the antenna, plasma, and waves interact in a manner that is not well-understood. We conducted a series of VLF transmission experiments in the radiation belts and measured the power and radiation impedance under various frequencies and conditions. The results demonstrate the critical role played by the plasma-antenna-wave interaction around high-voltage space antennae and open the possibility to transmit high power in space. The physical insight obtained in this study can provide guidance to future high-power space-borne VLF transmitter developments, laboratory whistler-mode wave injection experiments, and the interpretation of various astrophysical and optical phenomena.

Time-to-Event Analysis of Polatuzumab Vedotin-Induced Peripheral Neuropathy to Assist in the Comparison of Clinical Dosing Regimens.

Polatuzumab vedotin, an antibody-drug conjugate containing monomethyl auristatin E, was associated with an incidence of grade ≥2 peripheral neuropathy (PN) of 55-72% in patients with indolent non-Hodgkin lymphoma in a phase II study, when dosed 1.8-2.4 mg/kg every 3 weeks until progression or for a maximum of 17 cycles. To quantify the correlation of conjugate exposure and treatment duration with PN risk, a time-to-event model was developed using data from phase I and II studies. The model suggested that PN risk increased with conjugate exposure and treatment cycles, and a trend for increased risk with body weight and albumin concentration. When capping the treatment duration to six to eight cycles, the risk ratio of a dose of 2.4 mg/kg vs. 1.8 mg/kg was ≥1.29; the predicted incidence of grade ≥2 PN at 1.8-2.4 mg/kg dose levels was 17.8-37.2%, which is comparable with other antimicrotubule agents for lymphoma treatment.

On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass.

Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs' surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios.

Radially and azimuthally polarized laser induced shape transformation of embedded metallic nanoparticles in glass.

Radially and azimuthally polarized picosecond (~10 ps) pulsed laser irradiation at 532 nm wavelength led to the permanent reshaping of spherical silver nanoparticles (~30 - 40 nm in diameter) embedded in a thin layer of soda-lime glass. The observed peculiar shape modifications consist of a number of different orientations of nano-ellipsoids in the cross-section of each written line by laser. A Second Harmonic Generation cross-sectional scan method from silver nanoparticles in transmission geometry was adopted for characterization of the samples after laser modification. The presented approach may lead to sophisticated marking of information in metal-glass nanocomposites.

On the frequency-doubled conically-refracted Gaussian beam.

A Potassium Titanyl Phosphate (KTP) crystal has been used in conjunction with a 10-ps pulsed laser to produce a frequency-doubled conically-refracted Gaussian beam. The 'free' and 'forced' beams that make up the scheme for nonlinear conical refraction were readily observable in non-phase-matched conditions. The dependency of the frequency-doubled beam patterns on the incident beam polarization, which until now has remained unexplored, was examined in detail. We have also revealed the existence of two orthogonally polarized 'free' rays for particular orientations of the incident beam polarization.

Role of misalignment-induced angular chirp in the electro-optic detection of THz waves.

A general description of electro-optic detection including non-collinear phase matching and finite transverse beam profiles is presented. It is shown theoretically and experimentally that non-collinear phase matching in ZnTe (and similar materials) produces an angular chirp in the χ(2)-generated optical signal. Due to this, in non-collinear THz and probe arrangements such as single-shot THz measurements or through accidental misalignment, measurement of an undistorted THz signal is critically dependent on having sufficient angular acceptance in the optical probe path. The associated spatial walk-off can also preclude the phase retardation approximation used in THz-TDS. The rate of misalignment-induced chirping in commonly used ZnTe and GaP schemes is tabulated, allowing ready analysis of a detection system.

Azimuthally and radially polarized light in conical diffraction.

Azimuthal and radial polarization states of light are used to produce conical diffraction (CD) from a KGd(WO4)2 crystal. The patterns produced in the ring plane in each case display marked differences than those seen when linearly polarized incident light is used, with the production of a splitting of the CD ring into two concentric rings of equal intensity. The free space evolution for each type of polarization state is also experimentally recorded and investigated. Comparison with theory shows agreement with the experimentally observed results.

Picosecond pulsed laser induced optical dichroism in glass with embedded metallic nanoparticles.

Picosecond (~10 ps) pulsed laser irradiation at 532 nm led to the efficient and scalable fabrication of dichroic areas in glass with spherical silver nanoparticles of ~30 - 40 nm in diameter embedded in a surface layer of thickness ~20 µm. The observed dichroism is due to the uniform and permanent shape transformation of the nanoparticles - from spherical to spheroidal shapes - throughout the irradiated areas and along the laser polarization direction, paving the way for affordable manufacture of polarization-selective diffractive optical elements. The shape modification threshold and the dichroism as a result of Surface Plasmon Resonance band separation were identified. The process was then studied as a function of the laser polarization, repetition rate and the number of pulses fired per spot.

Diffractive optical element embedded in silver-doped nanocomposite glass.

A diffractive optical element is fabricated with relative ease in a glass containing spherical silver nanoparticles 30 to 40 nm in diameter and embedded in a surface layer of thickness ~10 µm. The nanocomposite was sandwiched between a mesh metallic electrode with a lattice constant 2 µm, facing the nanoparticle containing layer and acting as an anode, and a flat metal electrode as cathode. Applying moderate direct current electric potentials of 0.4 kV and 0.6 kV at an elevated temperature of 200 °C for 30 minutes across the nanocomposites led to the formation of a periodic array of embedded structures of metallic nanoparticles. The current-time dynamics of the structuring processes, optical analyses of the structured nanocomposites and diffraction pattern of one such fabricated element are presented.

Assessment of the ecological effects of arsenic on a southern Ohio, USA stream.

Davis Creek is a southern Ohio, USA stream that receives a permitted discharge from the Belpre Elastomers Plant (BEP). A sediment quality triad investigation of Davis Creek was conducted over a 2-y period that included sediment and surface water chemistry measurements, toxicity tests of whole sediment, interstitial and surface water, and benthic and artificial substrate community assessments. The concentration of arsenic in surface and interstitial water was below United States Environmental Protection Agency ambient water quality criteria and was not toxic in laboratory tests (Ceriodaphnia dubia, Pimephales promelas). Similarly, sediments did not significantly affect survival and growth of Hyalella azteca and Chironomus tentans at most sampling locations despite sediments exceeding arsenic sediment screening values in nearly all samples collected. Differences in benthic community structure, determined by rapid bioassessment and Hester-Dendy sampling methods, were related primarily by variations in sediment moisture, particle size, and ammonia and not to arsenic concentrations. The Invertebrate Community Index (ICI) for Davis Creek was lower than values established for other warm-water ecoregional reference streams in Ohio. However, this ICI comparison may have been invalid because, unlike the reference streams, the Davis Creek watershed is small with intermittent headwater flow that limits macroinvertebrate recruitment and energy input. The sediment quality triad investigation indicated that Davis Creek was not significantly affected by arsenic associated with the BEP discharge despite having measured arsenic concentrations that exceeded sediment screening values.

Benchmarking of electro-optic monitors for femtosecond electron bunches.

The longitudinal profiles of ultrashort relativistic electron bunches at the soft x-ray free-electron laser FLASH have been investigated using two single-shot detection schemes: an electro-optic (EO) detector measuring the Coulomb field of the bunch and a radio-frequency structure transforming the charge distribution into a transverse streak. A comparison permits an absolute calibration of the EO technique. EO signals as short as 60 fs (rms) have been observed, which is a new record in the EO detection of single electron bunches and close to the limit given by the EO material properties.

Temporally resolved electro-optic effect.

The electro-optic effect between an ultrafast optical probe pulse and an ultrashort terahertz pulse is shown to depend on the time derivatives of the product of the probe and terahertz electric fields. Application of this theory to temporally resolved single-shot terahertz detection techniques, where the electro-optic effect is temporally localized within an optical probe pulse, shows that the description presented here differs fundamentally and verifiably from that commonly used in literature.

Ultrastructure of smear layer-covered intraradicular dentin after irrigation with BioPure MTAD.

The structure of mechanically instrumented intraradicular dentin after irrigation with NaOCl as the initial rinse and BioPure MTAD as the final rinse were examined from the coronal, middle, and apical parts of root canal walls using transmission electron microscopy. Sterile distilled water and EDTA as final rinses were employed as the respective positive and negative controls under the same experimental conditions. There were 2 to 5 mum thick smear layers produced on mechanically instrumented root canal walls that were completely removed by EDTA and BioPure MTAD under agitation. Both irrigants created a zone of demineralized collagen matrices in eroded dentin and around the dentinal tubules, with the mildly acidic BioPure MTAD being more aggressive than EDTA. These demineralized dentin zones create the opportunity for dentin hybridization by infiltration of hydrophilic adhesives/sealers. However, the potential consequences of compaction of hydrophobic sealers against air-dried, collapsed collagen matrices, and hydrolytic degradation of incompletely infiltrated matrices remain unresolved.

Bondability of Resilon to a methacrylate-based root canal sealer.

Resilon broadens the dimensions of endodontic adhesion by introducing the possibility of creating monoblocs between root canal filling materials and intraradicular dentin by using methacrylate-based sealers. The adhesive strength of Resilon to RealSeal, a methacrylate-based root canal sealer, was evaluated using a modified microshear bond testing design. Flat Resilon surfaces with different roughness were created for bonding to the sealer and compared to a composite control. The composite control exhibited mean shear strength 7.3 to 26.9 times higher than those of the Resilon groups. Shear strength differences among the Resilon groups of different surface roughness highlighted the contribution of micromechanical versus chemical coupling in sealer retention. Ultrastructural evidence of phase separation of polymeric components in Resilon suggested that the amount of dimethacrylate incorporated into this filled, thermoplastic composite may not yet be optimized for effective chemical coupling to methacrylate-based sealers.

Vitamin D and vitamin D analogues for preventing fractures associated with involutional and post-menopausal osteoporosis.

BACKGROUND: Vitamin D and related compounds have been used to prevent fractures. OBJECTIVES: To determine the effects of vitamin D or analogues, with or without calcium, in the prevention of fractures in older people. SEARCH STRATEGY: We searched the Cochrane Bone, Joint and Muscle Trauma Group trials register, the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2005), MEDLINE, EMBASE, CINAHL, and reference lists of articles. Most recent search: March 2005. SELECTION CRITERIA: Randomised or quasi-randomised trials comparing vitamin D or an analogue, alone or with calcium, against placebo, no intervention, or calcium, reporting fracture outcomes, in older people. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality, and extracted data. Data were pooled, where admissible, using the fixed-effect model, or random-effects model if the relative risks were heterogeneous. MAIN RESULTS: Vitamin D alone showed no statistically significant effect on hip fracture (seven trials, 18,668 participants, RR 1.17, 95% CI 0.98 to 1.41), vertebral fracture (four trials, 5698 participants, RR (random effects) 1.13, 95% CI 0.50 to 2.55) or any new fracture (eight trials, 18,903 participants, RR 0.99, 95% CI 0.91 to 1.09). Vitamin D with calcium marginally reduced hip fractures (seven trials, 10,376 participants, RR 0.81, 95% CI 0.68 to 0.96), non-vertebral fractures (seven trials, 10,376 participants, RR 0.87, 95% CI 0.78 to 0.97), but there was no evidence of effect of vitamin D with calcium on vertebral fractures. The effect appeared to be restricted to those living in institutional care. Hypercalcaemia was more common when vitamin D or its analogues was given compared with placebo or calcium (14 trials, 8035 participants, RR 2.38, 95% CI 1.52 to 3.71). The risk was particularly high with calcitriol (three trials, 742 participants, RR 14.94, 95% CI 2.95 to 75.61). There was no evidence that vitamin D increased gastro-intestinal symptoms (seven trials, 10,188 participants, RR (random effects) 1.03, 95% CI 0.79 to 1.36) or renal disease (nine trials, 10,107 participants, RR 0.80, 95% CI 0.34 to 1.87). AUTHORS' CONCLUSIONS: Frail older people confined to institutions may sustain fewer hip and other non-vertebral fractures if given vitamin D with calcium supplements. Effectiveness of vitamin D alone in fracture prevention is unclear. There is no evidence of advantage of analogues of vitamin D compared with vitamin D. Calcitriol may be associated with an increased incidence of adverse effects. Dose, frequency, and route of administration of vitamin D in older people require further investigation.

Hip protectors for preventing hip fractures in older people.

BACKGROUND: Hip fracture in older people usually results from a fall on the hip. Hip protectors have been advocated as a means to reduce the risk of sustaining a hip fracture. OBJECTIVES: To determine if external hip protectors reduce the incidence of hip fractures in older people following a fall. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group trials register (January 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2005), MEDLINE (1966 to January Week 2, 2005), EMBASE (1988 to 2005 Week 02), CINAHL (1982 to December Week 2 2004), other databases and reference lists of relevant articles. We also contacted trialists. SELECTION CRITERIA: All randomised or quasi-randomised controlled trials comparing the use of hip protectors with a control group. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We sought additional information from trialists. Pooling of uncorrected data from cluster-randomised trials was only done on an exploratory basis. MAIN RESULTS: Fifteen included trials contributed data to this updated review. One trial, which was a study of compliance (adherence) lasting 12 weeks, contributed no fracture outcome data. Pooling of data from eleven trials conducted in nursing or residential care settings, including six cluster-randomised studies, showed evidence of a marginally statistically significant reduction in hip fracture incidence (relative risk (RR) 0.77, 95% confidence interval (CI) 0.62 to 0.97). This analysis showed significant statistical heterogeneity. Pooling of data from three individually randomised trials involving 5135 community dwelling participants, showed no reduction in hip fracture incidence from the provision of hip protectors (RR 1.16, 95% CI 0.85 to 1.59). There was no evidence of any significant effect of hip protectors on incidence of pelvic or other fractures. No important adverse effects of the hip protectors were reported but compliance, particularly in the long term, was poor. AUTHORS' CONCLUSIONS: Accumulating evidence casts some doubt on the effectiveness of the provision of hip protectors in reducing the incidence of hip in older people. Acceptance and adherence by users of the protectors remain poor due to discomfort and practicality.

Oral vitamin D3 and calcium for secondary prevention of low-trauma fractures in elderly people (Randomised Evaluation of Calcium Or vitamin D, RECORD): a randomised placebo-controlled trial.

BACKGROUND: Elderly people who have a fracture are at high risk of another. Vitamin D and calcium supplements are often recommended for fracture prevention. We aimed to assess whether vitamin D3 and calcium, either alone or in combination, were effective in prevention of secondary fractures. METHODS: In a factorial-design trial, 5292 people aged 70 years or older (4481 [85%] of whom were women) who were mobile before developing a low-trauma fracture were randomly assigned 800 IU daily oral vitamin D3, 1000 mg calcium, oral vitamin D3 (800 IU per day) combined with calcium (1000 mg per day), or placebo. Participants who were recruited in 21 UK hospitals were followed up for between 24 months and 62 months. Analysis was by intention-to-treat and the primary outcome was new low-energy fractures. FINDINGS: 698 (13%) of 5292 participants had a new low-trauma fracture, 183 (26%) of which were of the hip. The incidence of new, low-trauma fractures did not differ significantly between participants allocated calcium and those who were not (331 [12.6%] of 2617 vs 367 [13.7%] of 2675; hazard ratio (HR) 0.94 [95% CI 0.81-1.09]); between participants allocated vitamin D3 and those who were not (353 [13.3%] of 2649 vs 345 [13.1%] of 2643; 1.02 [0.88-1.19]); or between those allocated combination treatment and those assigned placebo (165 [12.6%] of 1306 vs 179 [13.4%] of 1332; HR for interaction term 1.01 [0.75-1.36]). The groups did not differ in the incidence of all-new fractures, fractures confirmed by radiography, hip fractures, death, number of falls, or quality of life. By 24 months, 2886 (54.5%) of 5292 were still taking tablets, 451 (8.5%) had died, 58 (1.1%) had withdrawn, and 1897 (35.8%) had stopped taking tablets but were still providing data for at least the main outcomes. Compliance with tablets containing calcium was significantly lower (difference: 9.4% [95% CI 6.6-12.2]), partly because of gastrointestinal symptoms. However, potentially serious adverse events were rare and did not differ between groups. INTERPRETATION: The findings do not support routine oral supplementation with calcium and vitamin D3, either alone or in combination, for the prevention of further fractures in previously mobile elderly people.

Electro-optic technique with improved time resolution for real-time, nondestructive, single-shot measurements of femtosecond electron bunch profiles.

Electro-optic detection of the Coulomb field of a relativistic electron bunch combined with single-shot cross correlation of optical pulses is used to enable single-shot measurements of the shape and length of femtosecond electron bunches. This method overcomes a fundamental time-resolution limit of previous single-shot electro-optic measurements, which arises from the inseparability of time and frequency properties of the probing optical pulse. Using this new technique we have made real-time measurements of a 50 MeV electron bunch, observing the profile of 650 fs FWHM ( approximately 275 fs rms) long bunches.

Patient-assessed health instruments for the knee: a structured review.

OBJECTIVES: To identify patient-assessed health instruments specific to the knee and review evidence for reliability, validity and responsiveness. METHODS: Instruments were identified through systematic searches of the literature. Information relating to instrument content, patient population, reliability, validity and responsiveness was extracted from published papers. RESULTS: The 16 instruments that met the inclusion criteria varied in length from 4 to 42 items. The majority form a single index; six produce a profile of scores. Eight have been evaluated in patients with a variety of knee problems. All instruments have satisfactory internal or test-retest reliability. However, there is limited empirical support for the health domains of six instruments. Patients informed the development of items within just five instruments. Few authors gave explicit consideration to the size of expected relationships in tests of construct validity. Eleven instruments have evidence for responsiveness to changes in health. The minimally important difference was not determined for any of the instruments. CONCLUSIONS: In the absence of comparative evidence, the large number of patient-assessed instruments for knee problems makes instrument selection difficult. The Knee Injury and Osteoarthritis Outcome Score (KOOS), Knee Pain Scale and Oxford Knee Score have good evidence for reliability, content validity and construct validity. The KOOS and Oxford instruments also have evidence for responsiveness. The instruments have not been evaluated for all knee problems, and instrument appropriateness, including content relevance, must be assessed before application. The comparative evaluation of instruments is recommended.

Hip protectors for preventing hip fractures in the elderly.

BACKGROUND: Hip fracture in the elderly usually results from a fall on the hip. Hip protectors have been advocated as a means to reduce the risk of sustaining a hip fracture. OBJECTIVES: To determine if external hip protectors reduce the incidence of hip fractures in elderly persons following a fall. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group trials register (February 2004), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2004), MEDLINE (1966 to February Week 2 2004), EMBASE (1988 to 2004 Week 08), CINAHL (1982 to February Week 2 2004), other databases and reference lists of relevant articles. We also contacted trialists. SELECTION CRITERIA: All randomised or quasi-randomised controlled trials comparing the use of hip protectors with a control group. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. We sought additional information from all trialists. MAIN RESULTS: An additional trial with 4169 participants was included in this update, giving a total of 14 included trials. One, which was a study of compliance (adherence) lasting 12 weeks, contributed no fracture outcome data. Five studies involving 4316 participants were cluster randomised by care unit, nursing home or nursing home ward rather than by the individual. Each of these studies reported a reduced incidence of hip fractures within those units allocated to receive the protectors. Because the majority of these trials had not been analysed to allow for clustering, pooling of their results was not undertaken. Pooling of data from five individually randomised trials conducted in nursing/residential care settings (1426 participants) showed no significant reduction in hip fracture incidence (hip protectors 37/822, controls 40/604, relative risk (RR) 0.83, 95% confidence interval (CI) 0.54 to 1.29). Three individually randomised trials of 5135 community dwelling participants, reported no reduction in hip fracture incidence with the hip protectors (RR 1.16, 95% CI 0.85 to 1.59). No important adverse effects of the hip protectors were reported but compliance, particularly in the long term, was poor. REVIEWERS' CONCLUSIONS: There is no evidence of effectiveness of hip protectors from studies in which randomisation was by individual patient within an institution, or for those living in their own homes. Data from cluster randomised studies indicate that, for those living in institutional care with a high background incidence of hip fracture, a programme of providing hip protectors appears to reduce the incidence of hip fractures. Acceptability by users of the protectors remains a problem, due to discomfort and practicality.