Acousto-optically Q-switched fibre laser source of high peak power and short duration pulses for fibre sensor applications

We report on a fibre laser source which emits high peak power (>0.7 kW) and short (2.8 ns) Q-switched pulses at 1.06 µm suitable for distributed fibre sensor applications using an absorbed pump power of 13 mW and miniature acousto-optic modulator

Pain and analgesic use associated with skeletal-related events in patients with advanced cancer and bone metastases

PURPOSE: Bone metastases secondary to solid tumors increase the risk of skeletal-related events (SREs), including the occurrence of pathological fracture (PF), radiation to bone (RB), surgery to bone (SB), and spinal cord compression (SCC). The aim of this study was to evaluate the impact of SREs on patients' pain, analgesic use, and pain interference with daily functioning. METHODS: Data were combined from patients with solid tumors and bone metastases who received denosumab or zoledronic acid across three identically designed phase 3 trials (N = 5543). Pain severity (worst pain) and pain interference were assessed using the Brief Pain Inventory at baseline and each monthly visit. Analgesic use was quantified using the Analgesic Quantification Algorithm. RESULTS: The proportion of patients with moderate/severe pain and strong opioid use generally increased in the 6 months preceding an SRE and remained elevated, while they remained relatively consistent over time in patients without an SRE. Regression analysis indicated that all SRE types were significantly associated with an increased risk of progression to moderate/severe pain and strong opioid use. PF, RB, and SCC were associated with significantly greater risk of pain interference overall. Results were similar for pain interference with emotional well-being. All SRE types were associated with significantly greater risk of pain interference with physical function. CONCLUSIONS: SREs are associated with increased pain and analgesic use in patients with bone metastases. Treatments that prevent SREs may decrease pain and the need for opioid analgesics and reduce the impact of pain on daily functioning

Pain and analgesic use associated with skeletal-related events in patients with advanced cancer and bone metastases

PURPOSE: Bone metastases secondary to solid tumors increase the risk of skeletal-related events (SREs), including the occurrence of pathological fracture (PF), radiation to bone (RB), surgery to bone (SB), and spinal cord compression (SCC). The aim of this study was to evaluate the impact of SREs on patients' pain, analgesic use, and pain interference with daily functioning. METHODS: Data were combined from patients with solid tumors and bone metastases who received denosumab or zoledronic acid across three identically designed phase 3 trials (N = 5543). Pain severity (worst pain) and pain interference were assessed using the Brief Pain Inventory at baseline and each monthly visit. Analgesic use was quantified using the Analgesic Quantification Algorithm. RESULTS: The proportion of patients with moderate/severe pain and strong opioid use generally increased in the 6 months preceding an SRE and remained elevated, while they remained relatively consistent over time in patients without an SRE. Regression analysis indicated that all SRE types were significantly associated with an increased risk of progression to moderate/severe pain and strong opioid use. PF, RB, and SCC were associated with significantly greater risk of pain interference overall. Results were similar for pain interference with emotional well-being. All SRE types were associated with significantly greater risk of pain interference with physical function. CONCLUSIONS: SREs are associated with increased pain and analgesic use in patients with bone metastases. Treatments that prevent SREs may decrease pain and the need for opioid analgesics and reduce the impact of pain on daily functioning

Light scattering from an isotropic layer between uniaxial crystals

We develop a model for the reflection and transmission of plane waves by an isotropic layer sandwiched between two uniaxial crystals of arbitrary orientation. In the laboratory frame, reflection and transmission coefficients corresponding to the principal polarization directions in each crystal are given explicitly in terms of the c-axis and propagation directions. The solution is found by first deriving explicit expressions for reflection and transmission amplitude coefficients for waves propagating from an arbitrarily oriented uniaxial anisotropic material into an isotropic material. By combining these results with Lekner's (1991) earlier treatment of waves propagating from isotropic media to anisotropic media and employing a matrix method we determine a solution to the general form of the multiple reflection case. The example system of a wetted interface between two ice crystals is used to contextualize the results.Comment: 18 pages, 9 figures,updated with changes made to published versio

Light transmission measurements in the liquid crystal SmC* phase of DOBAMBC at normal incidence

We present measurements of the light transmission of homeotropic smectic C* samples (DOBAMBC) at normal incidence as a function of temperature for different thicknesses in the whole spectral region where selective reflection occurs. Assuming that the transmission dip is a result of Bragg reflection, we obtain the temperature dependence of the pitch. The calculations of the reflection and transmission spectra using the 4 x 4 characteristic matrix showed good agreement between measured and calculated quantities.Nous présentons des mesures de transmission de lumière dans des échantillons homéotropes smectiques C* de DOBAMBC sous incidence normale pour différentes épaisseurs dans tout le domaine spectral où la réflexion sélective se produit. Supposant que la baisse de transmission résulte d'une réflexion de Bragg, nous obtenons la dépendanee en température du pas de l'hélice. Le calcul du spectre de réflexion/transmission utilisant la matrice caractéristique 4 x 4 montre un accord satisfaisant entre quantités mesurées et calculées

Selective reflection by helicoidal liquid crystals. results of an exact calculation using the 4 x 4 characteristic matrix method

The exact calculation of the reflection from single domain aligned samples of helicoidal liquid crystals (SmC* or cholesterics) is performed using the 4 x 4 matrix formulation of Maxwell equations in anisotropic media. We show that the expansion, approximation up to the 1st order of Berreman and Scheffer, is not adequate to describe the real situation, especially concerning the short wavelength region (heights of peaks, number of branches in the reflection band and their dependence on the different parameters).On présente un calcul exact de la réflexion de la lumière par un échantillon orienté de cristal liquide hélicoïdal (SmC* ou cholestérique) en utilisant la formulation matricielle 4 x 4 des équations de Maxwell pour les milieux anisotropes. On montre que la méthode approximative de Berreman et Scheffer est inadéquate, spécialement en ce qui concerne la région des faibles longueurs d'onde (nombre de pics, nombre de branches dans la bande de réflexion ainsi que leur dépendance avec les différents paramètres)

Elasto-optically induced modulation of in-fibre grating

We report on strong effects of uniaxial stress applied on in-fiber grating. Under the stress the reflection peak splits into two due to the elasto-optically induced birefringence. The separation between the two peaks increases with the stress, they broaden and shift. By modulating the pressure using a PZT disc at frequencies up to 1 MHz, we obtained modulation of the reflectivity which varies with the wavelength within the grating reflection band

Omnidirectional reflection from the one-dimensional photonic crystal containing anisotropic left-handed material

We study the transmission properties in the one-dimensional photonic crystal containing alternate anisotropic left-handed material (LHM) layers and regular isotropic right-handed material (RHM) layers. For such an anisotropic case, the dispersion relation from the Bloch theorem is derived and the Bragg gaps of the periodic structure are observed. It is found that in the m=0 Bragg gap, there is an omnidirectionally reflectional (ODR) region, which is also invariant with a change of scale length, similar with the $\bar{n}=0$ gap in isotropic one-dimensional photonic crystal. With the aid of effective medium theory (EMT), the analytic expressions of all six elements of the effective electric permittivity tensor and magnetic permeability tensor are obtained. By using these results, we investigate the ODR region in the m=0 Bragg gap in all the possible cases of both TE and TM modes. We find that with different choices of parameters, the m=0 Bragg gap has different transmission properties, and the ODR region in it changes, consequently. The edges of the ODR region are given out in these cases. To one's interest, these results predict a complete reflection region in the m=0 Bragg gap, which is able to omnidirectionally reflect waves in both TE and TM modes. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005

High power, short pulse acousto-optically Q-switched fibre laser

Short pulse, high peak power Q-switching of fibre lasers is demonstrated using a specially constructed TeO2 acousto-optic modulator with high diffraction efficiency at 1.06µm. The laser emits > 0.7 kW peak power pulses with 2.8ns duration at up to 1 kHz repetition rates for an absorbed pump power of 13 mW under zeroth order operation with average rf power of 50 mW. Under first order operation we obtained > 150 W peak power pulses with a 4ns duration using average rf driving power of 0.5 mW. Exact numerical integration of the laser kinetic rate equations yields good agreement with the experimental results

Magnetic-field-induced biaxiality in an antiferroelectric liquid crystal

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