An Integrated Pump-Controlled Variable Coupler Fabricated by Ultrafast Laser Writing.

The design and fabrication of a integrated symmetric directional coupler dependent o the pumping power and operating at a 1534 nm wavelength is reported. The twin-core waveguide was inscribed into Er3+/Yb3+ co-doped phosphate glass by a femtosecond laser direct writing technique. By optical pumping, the coupling ratio can be modulated due to the changes induced in the refractive index of the material. The experimental results demonstrated that the coupling ratio can be tuned continuously from 100/0 to 50/50 by increasing the pump's power from 0 to 350 mW. The developed twin-core coupler has promising applications for on-chip all-optical signal processing and communication systems.

Propagation Losses Estimation in a Cationic-Network-Based Hydrogel Waveguide.

A method based on the photographic recording of the power distribution laterally diffused by cationic-network (CN) hydrogel waveguides is first checked against the well-established cut-back method and then used to determine the different contributions to optical power attenuation along the hydrogel-based waveguide. Absorption and scattering loss coefficients are determined for 450 nm, 532 nm and 633 nm excitation. The excellent optical loss values obtained (0.32-1.95 dB/cm), similar to others previously described, indicate their potential application as waveguides in different fields, including soft robotic and light-based therapies.

Contribution to the Improvement of the Correlation Filter Method for Modal Analysis with a Spatial Light Modulator.

Modal decomposition of light is essential to study its propagation properties in waveguides and photonic devices. Modal analysis can be carried out by implementing a computer-generated hologram acting as a match filter in a spatial light modulator. In this work, a series of aspects to be taken into account in order to get the most out of this method are presented, aiming to provide useful operational procedures. First of all, a method for filter size adjustment based on the standard fiber LP-mode symmetry is presented. The influence of the mode normalization in the complex amplitude encoding-inherent noise is then investigated. Finally, a robust method to measure the phase difference between modes is proposed. These procedures are tested by wavefront reconstruction in a conventional few-mode fiber.

Effectiveness of low-frequency electrical stimulation in proprioceptive neuromuscular facilitation techniques in healthy males: a randomized controlled trial.

BACKGROUND: Hamstring muscle injuries are common in the sports field, with lack of hamstring flexibility being a risk factor. Stretching the hamstring muscles is an important part of the training and rehabilitation programs used to prevent or treat injury and improve performance. We aim to compare the immediate and follow-up effect on hamstring muscle flexibility between 2 different stretching protocols, proprioceptive neuromuscular facilitation (PNF) stretching and PNF stretching combined with electrostimulation. A second aim is to determine whether physical activity level is related to flexibility. METHODS: Design of study: Single-blind, randomized controlled trial; Participants: 30 healthy volunteers (30 men, 18-39 years old); Intervention: A 6-session intervention program spanning over 2 weeks and 1-week and 3-week follow-up. The control group underwent PNF stretching with a voluntary contraction. The experimental group underwent PNF stretching but the muscle contraction was triggered with an electrical stimulation device (TENS); Main outcome measu: Hamstring muscles flexibility was assessed using the Modified Sit and Reach (MSR) and the Back Saver Sit and Reach (BSSR) tests. Physical activity level was evaluated with the short form of the International Physical Activity Questionnaire (IPAQ). RESULTS: Both groups showed an overall increase in hamstring muscle flexibility. However, when comparing flexibility gain between baseline and the end of the stretching program (session 6), and at the 1-week and 3-week follow-ups, only the experimental group showed significant differences. No correlation between the IPAQ score and the degree of hamstring muscle flexibility was observed. CONCLUSIONS: Hamstring muscle PNF stretching combined with electrical stimulation to trigger muscle contraction during the muscle contraction phase of the stretch achieves better flexibility results when compared to PNF alone.

A kinetic study of Mg+ and Mg-containing ions reacting with O3, O2, N2, CO2, N2O and H2O: implications for magnesium ion chemistry in the upper atmosphere.

Reactions between Mg(+) and O(3), O(2), N(2), CO(2) and N(2)O were studied using the pulsed laser photo-dissociation at 193 nm of Mg(C(5)H(7)O(2))(2) vapour, followed by time-resolved laser-induced fluorescence of Mg(+) at 279.6 nm (Mg(+)(3(2)P(3/2)-3(2)S(1/2))). The rate coefficient for the reaction Mg(+) + O(3) is at the Langevin capture rate coefficient and independent of temperature, k(190-340 K) = (1.17 ± 0.19) × 10(-9) cm(3) molecule(-1) s(-1) (1σ error). The reaction MgO(+) + O(3) is also fast, k(295 K) = (8.5 ± 1.5) × 10(-10) cm(3) molecule(-1) s(-1), and produces Mg(+) + 2O(2) with a branching ratio of (0.35 ± 0.21), the major channel forming MgO(2)(+) + O(2). Rate data for Mg(+) recombination reactions yielded the following low-pressure limiting rate coefficients: k(Mg(+) + N(2)) = 2.7 × 10(-31) (T/300 K)(-1.88); k(Mg(+) + O(2)) = 4.1 × 10(-31) (T/300 K)(-1.65); k(Mg(+) + CO(2)) = 7.3 × 10(-30) (T/300 K)(-1.59); k(Mg(+) + N(2)O) = 1.9 × 10(-30) (T/300 K)(-2.51) cm(6) molecule(-2) s(-1), with 1σ errors of ±15%. Reactions involving molecular Mg-containing ions were then studied at 295 K by the pulsed laser ablation of a magnesite target in a fast flow tube, with mass spectrometric detection. Rate coefficients for the following ligand-switching reactions were measured: k(Mg(+)·CO(2) + H(2)O → Mg(+)·H(2)O + CO(2)) = (5.1 ± 0.9) × 10(-11); k(MgO(2)(+) + H(2)O → Mg(+)·H(2)O + O(2)) = (1.9 ± 0.6) × 10(-11); k(Mg(+)·N(2) + O(2)→ Mg(+)·O(2) + N(2)) = (3.5 ± 1.5) × 10(-12) cm(3) molecule(-1) s(-1). Low-pressure limiting rate coefficients were obtained for the following recombination reactions in He: k(MgO(2)(+) + O(2)) = 9.0 × 10(-30) (T/300 K)(-3.80); k(Mg(+)·CO(2) + CO(2)) = 2.3 × 10(-29) (T/300 K)(-5.08); k(Mg(+)·H(2)O + H(2)O) = 3.0 × 10(-28) (T/300 K)(-3.96); k(MgO(2)(+) + N(2)) = 4.7 × 10(-30) (T/300 K)(-3.75); k(MgO(2)(+) + CO(2)) = 6.6 × 10(-29) (T/300 K)(-4.18); k(Mg(+)·H(2)O + O(2)) = 1.2 × 10(-27) (T/300 K)(-4.13) cm(6) molecule(-2) s(-1). The implications of these results for magnesium ion chemistry in the atmosphere are discussed.

Kinetic studies of atmospherically relevant silicon chemistry. Part III: Reactions of Si+ and SiO+ with O3, and Si+ with O2.

Silicon ions are generated in the Earth's upper atmosphere by hyperthermal collisions of material ablated from incoming meteoroids with atmospheric molecules, and from charge transfer of silicon-bearing neutral species with major atmospheric ions. Reported Si(+) number density vs. height profiles show a sharp decrease below 95 km, which has been commonly attributed to the fast reaction with H(2)O. Here we report rate coefficients and branching ratios of the reactions of Si(+) and SiO(+) with O(3), measured using a flow tube with a laser ablation source and detection of ions by quadrupole mass spectrometry. The results obtained are (2σ uncertainty): k(Si(+) + O(3), 298 K) = (6.5 ± 2.1) × 10(-10) cm(3) molecule(-1) s(-1), with three product channels (branching ratios): SiO(+) + O(2) (0.52 ± 0.24), SiO + O(2)(+) (0.48 ± 0.24), and SiO(2)(+) + O (<0.1); k(SiO(+) + O(3), 298 K) = (6 ± 4) × 10(-10) cm(3) molecule(-1) s(-1), where the major products (branching ratio ≥ 0.95) are SiO(2) + O(2)(+). Reactions (1) and (2) therefore have the unusual ability to neutralise silicon directly, as well as forming molecular ions which can undergo dissociative recombination with electrons. These reactions, along with the recently reported reaction between Si(+) and O(2)((1)Δ(g)), largely explain the disappearance of Si(+) below 95 km in the atmosphere, relative to other major meteoric ions such as Fe(+) and Mg(+). The rate coefficient of the Si(+) + O(2) + He reaction was measured to be k(298 K) = (9.0±1.3) × 10(-30) cm(6) molecule(-2) s(-1), in agreement with previous measurements. The SiO(2)(+) species produced from this reaction, which could be vibrationally excited, is observed to charge transfer at a relatively slow rate with O(2), with a rate constant of k(298 K) = (1.5 ± 1.0) × 10(-13) cm(3) molecule(-1) s(-1).

Kinetic studies of atmospherically relevant silicon chemistry. Part II: silicon monoxide reactions.

Silicon monoxide (SiO) is injected directly into the Earth's upper atmosphere by ablating meteoroids. SiO is also produced by the reaction of atomic Si (another ablation product) with O(2) and O(3). The reactions of SiO with several atmospherically relevant oxidants have been studied by the pulsed laser photolysis of a Si atom precursor in the presence of O(2), followed by time-resolved non-resonant laser-induced fluorescence of SiO at 282 nm. This yielded: k(SiO + O(3), 190-293 K) = (4.4 +/- 0.6) x 10(-13) cm(3) molecule(-1) s(-1); k(SiO + O(2) + He, 293 K) < or = 3 x 10(-32) cm(6) molecule(-2) s(-1), k(SiO + O + He, 293 K) < or = 1 x 10(-30) cm(6) molecule(-2) s(-1), k(SiO + H(2)O, 293 K, 4-20 Torr) < or = 4 x10(-14) cm(3) molecule(-1) s(-1), and k(SiO + OH, 293 K, 4-20 Torr) = (5.7 +/- 2.0) x 10(-12) cm(3) molecule(-1) s(-1). These results are explained by combining ab initio quantum chemistry calculations with transition state theory and RRKM theory. An upper limit of 5 x 10(-13) cm(3) molecule(-1) s(-1) for the reaction SiO(2) + O --> SiO + O(2) was determined, but calculations indicate the existence of a high barrier (104.7 kJ mol(-1)) which will make this reaction very slow at mesospheric temperatures.

Kinetic studies of atmospherically relevant silicon chemistry part I: silicon atom reactions.

Atomic silicon is generated by meteoric ablation in the Earth's upper atmosphere (70-110 km). The reactions of Si(3P(J)) atoms with several atmospherically relevant species were studied by the pulsed laser photolysis of a Si atom precursor (typically PheSiH3), followed by time-resolved laser induced fluorescence at 251.43 nm (Si(3p2 3P0 --> 4s 3P1)). This yielded: k(Si + O2, 190-500 K) = 9.49 x 10(-11) + 1.80 x 10(-10) x exp(-T/115 K) cm3 molecule(-1) s(-1) (uncertainty < or = +/- 15%), in good accord with recent high-level theoretical calculations but in marked disagreement with previous experimental work; k(Si + O3, 190-293 K) = (4.0 +/- 0.5) x 10(-10) cm3 molecule(-1) s(-1); k(Si + CO2, 293 K) < or = 1.2 x 10(-14) cm3 molecule(-1) s(-1); and k(Si + H2O, 293 K) < or = 2.6 x 10(-13) cm3 molecule(-1) s(-1). These results are explained using a combination of quantum chemistry calculations and long-range capture theory. The quenching rate coefficients k(Si(1D2) + N2, 293 K) = (4.0 +/- 0.7) x 10(-11) cm3 molecule(-1) s(-1) and k(Si(1D2) + H2O, 293 K) = (2.3 +/- 0.3) x 10(-10) cm3 molecule(-1) s(-1) were also determined.

[Stapedotomy outcomes in the treatment of otosclerosis: our experience]. / Resultados de la estapedotomía en el tratamiento de la otosclerosis: nuestra experiencia.

OBJECTIVE: The main objective of our study is to identify whether there is measurable audiometric deterioration in patients undergoing stapedotomy with a follow-up of more than eight years. MATERIAL AND METHOD: We conducted a retrospective clinical study in which we reviewed a total of 150 case histories of patients with stapedotomy at our department between 1993 and 1997, with a successful initial audiological assessment using tone audiometry in the first three months after surgery and later audiometrical follow-up. RESULTS: We obtained a significant mean post-operative hearing impairment of 1.02 dB per year, with a pre-operative mean PTA of 51.45 dB, going on to early post-operative mean PTA of 26.71 dB, and later post-operative mean PTA of 35.42 dB, with all these changes turning out to be statistically significant. CONCLUSIONS: The auditory level obtained after surgery worsens as the years go by, but always without exceeding the hearing loss prior to surgery.

[Abnormal internal carotid artery in the middle ear and severe otorrhagia after myringotomy]. / Arteria carótida aberrante. A propósito de un caso.

We present a clinical-surgical case of a 72-year-old woman referred from another Hospital due to presentation of otorrhagia following myringotomy. We later determined by means of imaging studies that it was a case of an aberrant internal carotid artery. All masses in the middle ear, especially pulsing masses, must be studied by imaging methods such as computerized tomography and, preferably, magnetic resonance angiography.

Differences in cellular activation and apoptosis in HIV-infected patients receiving protease inhibitors or nonnucleoside reverse transcriptase inhibitors.

The mechanism of CD4(+) T cell depletion seen in HIV infection is largely mediated by increased apoptosis of these cells. The benefit of protease inhibitor (PI)-based antiretroviral therapy to CD4(+) T cell recovery seems to involve more than its antiviral activity, and a direct antiapoptotic effect of PIs has been proposed to explain it. To test this hypothesis we have analyzed directly, ex vivo, the effects of two different highly active antiretroviral therapy (HAART) regimens on the levels of activation and apoptosis of T lymphocytes. A total of 126 subjects (43 receiving PIs, 35 receiving NNRTIs, 27 untreated HIV carriers, and 21 uninfected control subjects) was included in the study. Apoptosis was measured in blood lymphocytes by flow cytometry, using annexin V labeling. A broad panel of monoclonal antibodies was used to characterize the different CD4(+) and CD8(+) lymphocyte subsets. Apoptosis was significantly increased in HIV-untreated subjects, whereas apoptosis levels did not differ when comparing HIV-positive subjects undergoing HAART and uninfected control subjects. Likewise, markers of activation were elevated in HIV-positive untreated patients, and declined in subjects receiving treatment. However, activated-memory CD8(+) T cells remained significantly higher in treated patients with respect to uninfected control subjects. No differences in the level of apoptosis or in immune activation markers were recognized when comparing subjects receiving PIs and those receiving NNRTIs. Antiretroviral therapy reduces apoptosis of CD4(+) and CD8(+) lymphocytes to normal levels without differences when comparing subjects receiving PI and NNRTI triple combinations. Despite complete suppression of viral replication, activated memory CD8(+) T cells remain significantly elevated in subjects receiving HAART, suggesting the persistence of residual HIV replication. If PIs provide a positive effect on CD4(+) counts beyond an antiviral effect, mechanisms other than apoptosis should be involved.

Traumatismo ocular en el niño: Repercusión visual / Eye injures in children: Visual impact

Se realizó un estudio que abarcó el quinquenio 1990-1994 en el Hospital General Docente de Morón a toda la población infantil afectada por traumatismos oculares que representó el 51,8 % de todos los pacientes ingresados. Se analiza el mecanismo de producción, la causa del accidente, la incapacidad visual, destacándose que el 23,7 % quedó con visión peor de 0,05, la mayor frecuencia fue en los varones 70,9 %, la edad más afectada fue en el grupo de 6-10 años (49,1 %). Se realizó una proyección epidemiológica alertando sobre la gravedad de ellos y su erradicación.

A study of the infantile population affected by eye injures, which accounted for 51,8 % of all admitted patients at the General Teaching Hospital of Moron from 1990-1994, was made. Mechanisms of occurence, causes of accidents and visual disability were analyzed and it was found out that the visual acuity in 23,7 % of children was under 0,05; the most affected were boys (70,9 %) and 6-10 years age group (49,1 %). An epidemiological project was carried out to alert on the seriousness of such eye injures and their erradication.