Effect of multiple scattering to optical forces on a sphere near an optical waveguide.

We have investigated the effect of multiple scattering to optical forces on a particle in the evanescent field produced by an optical waveguide. Considering the multiple scattering between the sphere and the waveguide, we extend the formalism based on transition matrix and reflection matrix to calculate the optical forces on a sphere near an optical waveguide. Numerical results show that the influence that multiple scattering has on the optical forces can't be ignored, especially when the structure resonance of the particle arises. Moreover, the effect of multiple scattering to optical forces is also studied in detail on the condition that the distance between the sphere and the waveguide is within the effective operating distance.

Morphology-dependent resonance of the optical forces on Mie particles in an Airy beam.

Morphology-dependent resonance (MDR) of the optical forces for a particle illuminated by Airy beams is investigated with respect to its internal field distribution. We find the ring structures arising from the resonance transform significantly with the parametric evolution of Airy evanescent wave, and the interference of the internal waves have a great impact on the Q factor and the background of the resonant peak, but it's not proper for Airy transmitted wave. The multiple reflections of the evanescent wave between the particle and the interface are also investigated, which show significant impacts on the region where the energy concentrate in.

The effects of multiple scattering to optical forces on a sphere in an evanescent field.

In this paper we discuss the effects of multiple scattering to the optical forces on a particle by an evanescent field. We show that the iterative method to process the effects of the interaction between the particle and a plane surface is invalid when the radius of particle is large or when the structural resonance of the particle occurs. By using the generalized minimum residual method to solve the set of equations directly, the divergence appears in the iterative method can be removed completely. As an illustrative example, we discussed the effects of multiple scattering to optical forces on a particle in an evanescent field from an incident plane wave. The interpretations of numerical results are presented in detail.

Optical forces on Mie particles in an Airy evanescent field.

Using vector potential and spectrum representation, we derive the expressions of the Airy evanescent field existed at the interface. Utilizing these expressions and the Arbitrary Beam Theory, the optical forces exerted on a Mie dielectric particle in the Airy evanescent field were theoretically investigated in detail. Numerical results show that the optical forces exhibit strong oscillations which are corresponding to the distributions of the evanescent field. With the increasing the size of particle radius, Morphology Dependent Resonance occurs for the particle with specific refractive index.

Vacuum electron acceleration driven by a tightly focused radially polarized Gaussian beam.

Electron acceleration in vacuum driven by a tightly focused radially polarized Gaussian beam has been studied in detail. Weniger transformation method is used to eliminate the divergence of the radially polarized electromagnetic field derived from the Lax series approach. And, electron dynamics in an intense radially polarized Gaussian beam is analyzed by using the Weniger transformation field. The roles of the initial phase of the electromagnetic field and the injection angle, position and energy of electron in energy gain of electron have been studied in detail.

Vacuum electron acceleration driven by two crossed Airy beams.

Using numerical simulation, we have studied in detail vacuum electron acceleration driven by two crossed Airy beams with identical characteristics except for opposite accelerating directions. An electron injected along the longitudinal central axis is only affected by the combined longitudinal electric field. In addition, a suitable crossed Airy beams scheme is more beneficial to the energy gain of an electron than the single Airy beam acceleration scheme [Opt. Lett. 35, 3258 (2010)]. Meanwhile, the cross angle, the injection energy of the electron, and the initial phase of the Airy beams play significant roles in the energy gain of the electron.

Correlation of synovial fluid HMGB-1 levels with radiographic severity of knee osteoarthritis.

PURPOSE: This study measured high-mobility group box 1 (HMGB-1) levels in serum and synovial fluid (SF) in patients with primary knee osteoarthritis (OA) and correlated these levels with radiographic disease severity. METHODS: Seventy-eight OA patients and 30 controls were enrolled in this study. All OA patients were scored according to the Kellgren-Lawrence (KL) grading system. HMGB-1 levels were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: SF HMGB-1 levels were significantly higher in knee OA patients, compared with controls (P < 0.01). Moreover, SF HMGB-1 levels were positively associated with KL scores (P < 0.01). Multinomial logistic regression demonstrated that the SF HMGB-1 level was an independent factor for radiographic severity of OA (P=0.002); however, serum HMGB-1 levels did not differ significantly between OA patients and controls and did not correlate with KL scores (P > 0.05). CONCLUSION: These results demonstrate that HMGB-1 levels in SF of knee OA patients are independently associated with radiographic disease severity.

Vacuum laser-driven acceleration by Airy beams.

The possibility of enhancing the energy gain in vacuum electron acceleration by Airy beams is examined. The characteristics of transverse acceleration and non-diffraction of Airy beam can lead to the formation of a long "asymmetric field channel" along the propagation axis, where the intense asymmetric field can accelerate the injected electron to higher energy. Meanwhile, the injection energy of electron plays an important role in determining the final energy gain.

Modified elliptically polarized light Z-scan method for studying third-order nonlinear susceptibility components.

The normal elliptically polarized light Z-scan method is modified by adding a quarter-wave plate and an analyzer before the detector. The normalized transmittance formulas of modified elliptically polarized light Z-scan are obtained for media with negligible nonlinear absorption. Compared with normal linearly and elliptically polarized light Z-scan methods, an increase of sensitivity by a factor of larger than 4 is achieved for the real part of third-order susceptibility component's measurements using this modified elliptically polarized light Z-scan method. The analytical results are verified by studying the real part of independent susceptibility components of CS(2) liquid. Moreover, the potential application for cross-polarized wave generation is discussed.

Analysis of electron capture acceleration channel in an Airy beam.

Using numerical simulation, we have studied in detail vacuum electron acceleration induced by an Airy beam. The phase of the field varies slowly, and the intensity of the field is independent of the decaying parameter of the beam in the asymmetric field channel [(AFC) Opt. Express 18, 7300 (2010)] formed by the Airy beam. Results show that an electron entering into the AFC may be captured and gain high energy. Meanwhile, the decaying parameter, injection energy, and injection angle of the electron play important roles in the electron energy gain.

Acceleration of electrons by a tightly focused intense laser beam.

The recent proposal to use Weinger transformation field (WTF) [Opt. Express 17, 4959-4969 (2009)] for describing tightly focused laser beams is investigated here in detail. In order to validate the accuracy of WTF, we derive the numerical field (NF) from the plane wave spectrum method. WTF is compared with NF and Lax series field (LSF). Results show that LSF is accurate close to the beam axis and divergent far from the beam axis, and WTF is always accurate. Moreover, electron dynamics in a tightly focused intense laser beam are simulated by LSF, WTF and NF, respectively. The results obtained by WTF are shown to be accurate.

[Combined pedicle subtraction osteotomy and polysegmental closing wedge osteotomy for correction of the severe thoracolumbar kyphotic deformity in ankylosing spondylitis].

OBJECTIVE: To study retrospectively the efficacy and complications of combined pedicle subtraction osteotomy (PSO) and polysegmental closing wedge osteotomy for correction of the severe rigid thoracolumbar kyphotic deformity in ankylosing spondylitis (AS). METHODS: A total of 8 consecutive male patients with AS and severe thoracolumbar kyphotic deformity (mean age 32 years, range 28 - 46) were involved in this study from August 2004 to June 2007. The average preoperative Cobb angle of thoracic spine (T(1)-T(12)) was 96 degrees (range, 80 degrees - 112 degrees ), the mean preoperative angle of lumbar lordosis (L(1)-S(1)) was 10 degrees (5 degrees - 15 degrees ). The mean chin-brow angle was 47 degrees (range, 40 degrees - 58 degrees ). The average gaze angle was 43 degrees (range, 32 degrees - 50 degrees ). After preoperative assessment, single-level PSO was performed in L(3) vertebrae and two-level polysegmental closing wedge osteotomy was performed in thoracolumbar vertebrae (T(12)-L(1), L(1-2)). Radiographic and clinical results and complications were assessed. RESULTS: The surgical time was (298.1 +/- 20.7) minutes and blood loss during the procedure was (1588.8 +/- 171.6) ml. The follow-up period was (11.5 +/- 7.7) months. The postoperative angle and the amount of correction of the thoracic and lumbar spine were 76.1 degrees +/- 9.6 degrees , 20.3 degrees +/- 1.1 degrees and 48.4 degrees +/- 4.7 degrees , 38.4 degrees +/- 4.7 degrees respectively. The postoperative chin-brow and gaze angle was 16.5 degrees +/- 4.6 degrees and 73.0 degrees +/- 5.2 degrees , respectively. The amount of correction for sagittal balance was (12.3 +/- 1.6) cm. No nerve, vascular injury, stress fracture and coronal decompensation occurred in the patients. CONCLUSIONS: Combined PSO and polysegmental closing wedge osteotomy by posterior approach only is safe and effective for correction of the severe rigid thoracolumbar kyphotic deformity in AS. The visual field is significantly improved after surgery.

Nonlinear ellipse rotation modified Z-scan measurements of third-order nonlinear susceptibility tensor.

We present a method that combines the Z-scan technique with nonlinear ellipse rotation (NER) to measure third-order nonlinear susceptibility components. The experimental details are demonstrated, and a comprehensive theoretical analysis is given. The validity of this method is verified by the measurements of the nonlinear susceptibility tensor of a well-characterized liquid, CS2.

Periodic dielectric bars assisted enhanced transmission and directional light emission from a single subwavelength slit.

The transmission from a single subwavelength slit in a metal film with periodic dielectric bars on its surfaces has been analyzed numerically by the finite-difference time-domain method. Results show that the role of the periodic dielectric bars is just the same as that of the periodic grooves directly on the surfaces. With the modulations of dielectric bars on the input and output surfaces of the metal film, light transmission through the subwavelength slit is enhanced extraordinarily and confined to directional emission. The CDEW model is employed to explain the mechanism of the transmission enhancement and directional emission caused by the periodic dielectric bars.

[A high sensitivity optical multichannel analyzer].

Noise sources of the CCD as the photoelectric detection device in an optical multichannel analyzer (OMA) were analyzed, and noise suppression methods were discussed. A high sensitivity OMA was developed successfully on the basis of the noise suppression techniques, and the 7th spectral lines of Balmer series of hydrogen and deuterium were resolved clearly by the OMA. Its sensitivity was enhanced by one order of magnitude, compared with those reported in the literatures. This OMA also showed high resolution, high precision and good reliability in the authors' experiments.

Posterior unilateral pedicle subtraction osteotomy of hemivertebra for correction of the adolescent congenital spinal deformity.

BACKGROUND CONTEXT: The treatment of adolescent congenital deformity (late-diagnosed congenital deformity) is still unknown. The best candidates for hemivertebra excision are young patients, typically between 4 and 6 years of age. Partial excision may be feasible for older children. PURPOSE: The purpose of this study was to assess the effect of unilateral pedicle subtraction osteotomy of hemivertebra for correction of the adolescent congenital spinal deformity. STUDY DESIGN: Retrospective analysis. PATIENT SAMPLE: Twelve patients with adolescent congenital deformity who underwent posterior unilateral pedicle subtraction osteotomy and correction were evaluated. Mean age at the time of surgery was 17 years. OUTCOME MEASURES: The charts, standing full-length posteroanterior and lateral view radiographs, and functional measures were reviewed. METHODS: For evaluation of surgical effectiveness, comparative analysis of the parameters of the total main curve, the segmental curve, the compensatory cranial and caudal curves, the segmental kyphosis, and the trunk shift before and after operation and at the most recent follow-up was done. RESULTS: The mean follow-up period was 40.5 months. Mean Cobb angles of the total main curve and the segmental curve were, respectively, 47.5° and 43.8° before surgery, 23.7° and 16.5° after surgery, and 22.6° and 17° at the last follow-up. The angle of segmental kyphosis was 11.8° before surgery, 6.2° after surgery, and 7.8° (range, -30° to 26°) at the final follow-up. The mean final global lordosis was within the normal range. No neurologic deficit occurred. Solid fusion was achieved for all cases. CONCLUSIONS: Unilateral pedicle subtraction osteotomy with instrumentation from a posterior-only approach is indicated in older teenagers for an adolescent congenital spinal deformity. Compared with hemivertebra excision, corrective surgery with hemivertebra osteotomy has a lower intraoperative blood loss and shorter operation time.

Dynamic response of the idiopathic scoliotic spine to axial cyclic loads.

STUDY DESIGN: Numerical techniques were used to study the vibration response of idiopathic scoliosis patients with single thoracic curve. OBJECTIVE: To analyze the dynamic characteristics of the idiopathic scoliotic spine under the whole-body vibration condition. The influence of the upper body mass was also studied. SUMMARY OF BACKGROUND DATA: The relationship between the whole-body vibration and the spinal disorders has been investigated using finite element method. However, the dynamic response features of the scoliotic spine to the vibration were poorly understood. METHODS: The resonant frequencies of the scoliotic spine and the effects of the body weight were studied using a finite element model described previously. Modal and harmonic analysis was conducted. The amplitudes of 6 fundamental vertebral movements around the long, coronal and sagittal axis were quantified in the frequency range of 1 to 35 Hz. RESULTS: The vibration-induced rotation amplitudes of the apex of the thoracic deformity were higher than that of the lumbar segments. The apical vertebrae had the greatest rotation amplitudes at 2 and 8 Hz, and the largest lateral translation amplitudes at 16 Hz. Vibration could cause large lateral flexion amplitudes in the apex of the thoracic deformity. The apical vertebrae had the largest side flexion amplitudes at 6 Hz. Increasing upper body mass could not change resonant frequency of vibration-induced lateral translation and rotation around the long axis of the apical vertebrae. CONCLUSION: The scoliotic spine is more sensitive to vibration than the normal spine. For a patient with single thoracic curve, long-term whole-body vibration may do more harm to the thoracic deformity than to the lower lumbar segments. Axial cyclic loads applied to an already deformed spine may cause further rotational and scoliotic deformity. The patients with idiopathic scoliosis are more likely to suffer from vibration-induced spinal disorders than those by normal persons.

[Efficacy of DACE regimen on relapsed and refractory non-Hodgkin's lymphoma].

BACKGROUND & OBJECTIVE: There is no standard salvage regimen for patients with relapsed and refractory non-Hodgkin's lymphoma (NHL) at present. This study was to evaluate the efficacy of DACE regimen, as a salvage regimen, on relapsed and refractory NHL, and observe the adverse events. METHODS: From May 2001 to May 2006, 61 patients with relapsed and refractory NHL received chemotherapy of DACE regimen: intravenous infusion of cisplatin (20 mg/m(2)) on Days 1-5, etoposide (100 mg) on Days 1-5, cytarabine (150 mg) on Days 1-3, and dexamethone (15 mg/m(2)) on Days 1-5; repeated every 3 weeks. The efficacy and adverse events were evaluated according to the World Health Organization criteria. RESULTS: The overall response rates were 63.9% after two cycles of chemotherapy and 72.1% after four cycles. The median remission time lasted 4.7 months (1-58 months). The 1-year survival rate was 29.5%û the 2-year survival rate was 21.3%. Myelosuppression was the major adverse event: the occurrence rate of grade III-IV myelosuppression was 49.1%û it was well tolerated. CONCLUSION: DACE regimen is an effective salvage regimen in treating patients with relapsed and refractory NHL.

Local one-dimensional approximation for fast simulation of Z-scan measurements with an arbitrary beam.

We apply a finite-difference algorithm that combines the local one-dimensional approximation and the Crank-Nicolson algorithms to solve the three-dimensional nonlinear Schrödinger equation. This scheme is unconditionally stable and accurate to second order. Therefore it offers a simple and accurate means to study a two-dimensional Z scan for arbitrary beam shape and medium length. As an example, we analyze the characteristics of a Z scan by utilizing an elliptic Gaussian beam for a thick nonlinear medium. The effects of ellipticity and waist separation of the elliptic beam on the normalized transmittance of the closed-aperture and open-aperture Z scan are demonstrated.

Comparison of the solutions from a novel variational method with numerical results for the study of beam propagation in a Kerr medium with nonlinear absorption.

We present results from a novel variational method for the study of beam propagation in a Kerr medium with nonlinear absorption. This new method combines the variational method and a nonlinear absorption equation and gives a concise expression for the combination. The results obtained with this method show good quantitative agreement with numerical solutions obtained with the finite-difference method. It is shown that the variational method takes much less time than a numerical simulation with the finite-difference method for analysis of beam propagation in a thick medium with nonlinear absorption and nonlinear refraction. The new method makes detailed analysis of beam propagation in a Kerr medium with nonlinear absorption very simple and fast.