Ultrafast Loss of Lattice Coherence in the Light-Induced Structural Phase Transition of V_{2}O_{3}.

In solids, the response of the lattice to photoexcitation is often described by the inertial evolution on an impulsively modified potential energy surface which leads to coherent motion. However, it remains unknown if vibrational coherence is sustained through a phase transition, during which coupling between modes can be strong and may lead to rapid loss of coherence. Here we use coherent phonon spectroscopy to track lattice coherence in the structural phase transition of V_{2}O_{3}. In both the low and high symmetry phases unique coherent phonon modes are generated at low fluence. However, coherence is lost when driving between the low and high symmetry phases. Our results suggest strongly damped noninertial dynamics dominate during the phase transition due to disorder and multimode coupling.

Realization of macroscopic ratchet effect based on nonperiodic and uneven potentials.

Ratchet devices allow turning an ac input signal into a dc output signal. A ratchet device is set by moving particles driven by zero averages forces on asymmetric potentials. Hybrid nanostructures combining artificially fabricated spin ice nanomagnet arrays with superconducting films have been identified as a good choice to develop ratchet nanodevices. In the current device, the asymmetric potentials are provided by charged Néel walls located in the vertices of spin ice magnetic honeycomb array, whereas the role of moving particles is played by superconducting vortices. We have experimentally obtained ratchet effect for different spin ice I configurations and for vortex lattice moving parallel or perpendicular to magnetic easy axes. Remarkably, the ratchet magnitudes are similar in all the experimental runs; i. e. different spin ice I configurations and in both relevant directions of the vortex lattice motion. We have simulated the interplay between vortex motion directions and a single asymmetric potential. It turns out vortices interact with uneven asymmetric potentials, since they move with trajectories crossing charged Néel walls with different orientations. Moreover, we have found out the asymmetric pair potentials which generate the local ratchet effect. In this rocking ratchet the particles (vortices) on the move are interacting each other (vortex lattice); therefore, the ratchet local effect turns into a global macroscopic effect. In summary, this ratchet device benefits from interacting particles moving in robust and topological protected type I spin ice landscapes.

Little-Parks effect governed by magnetic nanostructures with out-of-plane magnetization.

Little-Parks effect names the oscillations in the superconducting critical temperature as a function of the magnetic field. This effect is related to the geometry of the sample. In this work, we show that this effect can be enhanced and manipulated by the inclusion of magnetic nanostructures with perpendicular magnetization. These magnetic nanodots generate stray fields with enough strength to produce superconducting vortex-antivortex pairs. So that, the L-P effect deviation from the usual geometrical constrictions is due to the interplay between local magnetic stray fields and superconducting vortices. Moreover, we compare our results with a low-stray field sample (i.e. with the dots in magnetic vortex state) showing how the enhancement of the L-P effect can be explained by an increment of the effective size of the nanodots.

Relaxor ferroelectricity and magnetoelectric coupling in ZnO-Co nanocomposite thin films: beyond multiferroic composites.

ZnO-Co nanocomposite thin films are synthesized by combination of pulsed laser deposition of ZnO and Co ion implantation. Both superparamagnetism and relaxor ferroelectricity as well as magnetoelectric coupling in the nanocomposites have been demonstrated. The unexpected relaxor ferroelectricity is believed to be the result of the local lattice distortion induced by the incorporation of the Co nanoparticles. Magnetoelectric coupling can be attributed to the interaction between the electric dipole moments and the magnetic moments, which are both induced by the incorporation of Co. The introduced ZnO-Co nanocomposite thin films are different from conventional strain-mediated multiferroic composites.

Treatment of traumatic corneal abrasions: a three-arm, prospective, randomized study.

PURPOSE: To compare three different treatment modalities for traumatic corneal abrasions. METHODS: We conducted a prospective, randomized, masked, three-arm clinical study of patients presenting with superficial corneal foreign bodies. Treatment modalities were: (1) pressure patching with ofloxacin ointment (patch group, PG, n = 18), (2) therapeutic contact lens with ofloxacin eye drops (contact lens group, CLG, n = 20) and (3) ofloxacin ointment alone (ointment group, OG, n = 28). Primary outcome measure was the difference of the mean corneal abrasion area between the three groups at 3 different time points (baseline, day 1 and day 7). RESULTS: A total of 66 patients were included in the study over a period of 2 years. Mean initial corneal abrasion area was 3.6 ± 3.4 mm² in the PG, 4.2 ± 4.0 mm² in the CLG and 3.7 ± 3.1 mm² in the OG (p = 0.875). Differences in corneal abrasion area at any time point were not statistically significant (abrasion area decrease from presentation to day 1 was 3.4 ± 3.3 mm² in the PG, 4.1 ± 4.0 mm² in the CLG and 3.5 ± 3.1 mm² in the OG, p = 0.789). The epithelium was healed in all patients at day 7. CONCLUSIONS: Treating traumatic corneal abrasions by pressure patching, a bandage contact lens or ointment alone was equal in reducing the abrasion area or reducing pain. According to our results the treatment of choice for traumatic abrasions may be adapted to the needs and preferences of the patient.

The predictive value of OCT characteristics for the visual outcome in neovascular AMD.

BACKGROUND: The intravitreal injection of an anti-VEGF compound is the current standard of care in neovascular AMD. The response to this therapy varies greatly. To date it was not possible to determine clear predictive factors in regard to therapy response, thus making it difficult when counselling patients regarding the probability for visual improvement. The aim of this study was to evaluate baseline OCT characteristics in regard to their predictive value on the outcome of visual acuity (VA) after 12 months. PATIENTS AND METHODS: A retrospective analysis of 75 eyes with neovascular AMD treated with intravitreal anti-VEGF injections at the University Hospital of Zurich with a documented follow-up of at least 12 months. Measurement and comparison of the following OCT structures were undertaken: central retinal thickness (CRT), integrity of the IS/OS junction, and presence of intra- or subretinal fluid. VA at baseline and after 12 months was evaluated. OCT findings were compared between eyes that gained ≥ 5 letters ETDRS (group 1) and eyes that did not (group 2). RESULTS: 75 eyes with a mean baseline VA of 57.2 ± 15 letters and a mean baseline CRT of 430 ± 226 µm were analyzed. Although baseline VA did not differ statistically significantly, eyes in group 2 had a higher VA than eyes in group 1 (60.2 ± 16.2 vs. 54.9 ± 13.6, p = 0.123). In group 1 the change of VA after 12 months was 12.6 ± 8.0 letters while it was -5.0 ± 7.8 letters in group 2. No statistically significant differences between the two groups with respect to the analyzed OCT parameters were found. None of the analyzed OCT factors had a predictive value regarding the VA outcome at month 12. CONCLUSIONS: Our study was not able to find baseline OCT parameters that could predict the course of VA after 12 months. However, eyes with a thicker central retinal thickness at presentation showed a greater reduction in CRT during the analyzed period. This was associated with a more favourable course in VA. Perhaps this might be due to a less pronounced initial morphological retinal damage.

Tuning quantum corrections and magnetoresistance in ZnO nanowires by ion implantation.

Using ion implantation, the electrical as well as the magnetotransport properties of individual ZnO nanowires (NWs) can be tuned. The virgin NWs are configured as field-effect transistors which are in the enhancement mode. Al-implanted NWs reveal a three-dimensional metallic-like behavior, for which the magnetoresistance is well described by a semiempirical model that takes into account the presence of doping induced local magnetic moments and of two conduction bands. On the other hand, one-dimensional electron transport is observed in Co-implanted NWs. At low magnetic fields, the anisotropic magnetoresistance can be described in the framework of weak electron localization in the presence of strong spin-orbit scattering. From the weak localization, a large phase coherence length is inferred that reaches up to 800 nm at 2.5 K. The temperature-dependent dephasing is shown to result from a one-dimensional Nyquist noise-related mechanism. At the lowest temperatures, the phase coherence length becomes limited by magnetic scattering.

Unexpected optical response of single ZnO nanowires probed using controllable electrical contacts.

Relying on combined electron-beam lithography and lift-off methods Au/Ti bilayer electrical contacts were attached to individual ZnO nanowires (NWs) that were grown by a vapor phase deposition method. Reliable Schottky-type as well as ohmic contacts were obtained depending on whether or not an ion milling process was used. The response of the ZnO NWs to ultraviolet light was found to be sensitive to the type of contacts. The intrinsic electronic properties of the ZnO NWs were studied in a field-effect transistor configuration. The transfer characteristics, including gate threshold voltage, hysteresis and operational mode, were demonstrated to unexpectedly respond to visible light. The origin of this effect could be accounted for by the presence of point defects in the ZnO NWs.

Response to ranibizumab therapy in neovascular AMD - an evaluation of good and bad responders.

BACKGROUND: Treatment of neovascular age-related macular degeneration (AMD) with Lucentis shows a broad spectrum regarding the course of visual acuity (VA). While some patients show a good response (increase in VA), others disclose much less promising results. PATIENTS AND METHODS: A retrospective data analysis of all eyes treated for neovascular AMD at the University Hospital of Zurich, Switzerland for at least 12 months was carried out. The courses of VA between the 90th (good responders, GR) and the 10th (bad responders, BR) percentiles were compared at 3, 12 and 24 months from baseline. An analysis regarding demographic data, lesion type and size as well as injection frequency and visits was done and predictive factors for GR and BR were evaluated. RESULTS: Marked differences in the course of VA between GR (n = 30) and BR (n = 30) are already observed 3 months from baseline. In GR the gains in VA after 3, 12 and 24 were 15.7 +/- 9 letters ETDRS, 25.3 +/- 7 and 14.0 +/- 14. BR showed a deterioration of 8.3 +/- 11 letters ETDRS after 3, 22.1 +/- 8 after 12 and 23.6 +/- 13 after 24 months. The gender distribution was equal with a higher percentage of female patients (64 % in BR and 66 % in GR). The baseline VA was statistically significantly lower in GR (45.7 +/- 10 vs. 55.4 +/- 11, p < 0.05) than in BR. No other significant differences in baseline data were found, and no predictor for group membership could be identified. CONCLUSIONS: Only the course of VA in the first three months seems to be of value for an estimation of the response to treatment. In the future the response to treatment in the early phase may influence the treatment algorithm and the injection frequency.

First clinical experience with anecortave acetate (Retaane).

BACKGROUND: Anecortave acetate is an angiostatic cortisene which is injected as a posterior juxtascleral depot and has been shown to be effective in the treatment of exudative age-related macular degeneration (AMD). The compound is not yet approved in Switzerland but can be used as "compassionate use" in individual cases. PATIENTS AND METHODS: An uncontrolled case series with standardised documentation of ETDRS visual acuity, near acuity, need for magnification and fluorescein angiography was performed. RESULTS: 22 eyes of 19 patients (8 male, 11 female, average age 78.8 years) were treated with a posterior juxtascleral depot injection (PJD) of 15 mg anecortave acetate. The mean change in visual acuity after 3 months in eyes treated with anecortave acetate was -2.6 ETDRS letters corresponding to 0.52 Snellen lines. 3/20 eyes gained more than 1 line. 11/20 eyes showed stable visual acuity (+/- 1 Snellen line, +/- 5 ETDRS letters). 5/20 eyes developed moderate vision loss (one to two Snellen lines, 6-10 ETDRS letters). 1/20 lost 18 ETDRS letters (> 3 Snellen lines). There were no moderate or severe adverse events. CONCLUSIONS: A PJD of 15 mg anecortave acetate is safe and well tolerated. In eyes with occult CNV without recent progression or with residual neovascular activity after photodynamic therapy anecortave acetate may be an alternative therapeutic option before considering intravitreal anti-VEGF agents due to the much less invasive character and lower risk profile.

[Does cataract surgery increase the risk of exudative age-related macular degeneration? Results from a large retrospective case-control study]. / Besteht ein Zusammenhang zwischen einer Kataraktoperation und nachfolgender exsudativer altersbedingter Makuladegeneration? Eine grosse retrospektive Fallkontrollstudie.

BACKGROUND: Many epidemiological studies indicate a positive correlation between cataract surgery and the subsequent progression of age-related macular degeneration (AMD). Such a correlation would have far-reaching consequences. However, in epidemiological studies it is difficult to determine the significance of a single risk factor, such as cataract surgery. PATIENTS AND METHODS: We performed a retrospective case-control study of patients with new onset exudative age-related macular degeneration to determine if cataract surgery was a predisposing factor. A total of 1496 eyes were included in the study: 984 cases with new onset of exudative AMD and 512 control eyes with early signs of age-related maculopathy. Lens status (phakic or pseudophakic) was determined for each eye. RESULTS: There was no significant difference in lens status between study and control group (227/984 [23.1 %] vs. 112/512 [21.8 %] pseudophakic, p = 0.6487; OR = 1.071; 95 % CI = 0.8284-1.384). In cases with bilateral pseudophakia (n = 64) no statistically significant difference of the interval between cataract surgery in either eye and the onset of exudative AMD in the study eye was found (225.9 +/- 170.4 vs. 209.9 +/- 158.2 weeks, p = 0.27). CONCLUSIONS: Our results provide evidence that cataract surgery is not a major risk factor for the development of exudative AMD.

Commensurability and stability in nonperiodic systems.

We have investigated the response of 3D Bi(2)Sr(2)CaCu(2)O(8) vortex structures to a weak perturbation induced by 2D Fe pinning structures acting on one extremity of vortex lines. The pinning patterns were nano-engineered at the sample surface by means of either a Bitter decoration of the vortex lattice or electron-beam lithography. The commensurability conditions between 2D rigid pinning potentials and 3D elastic structures with short-range positional and long-range orientational correlation have been experimentally determined. When the 2D potential is a replica of the nonperiodic vortex structure an amplification of its interaction with the vortex structure takes place. This effect is detected only for the first matching field, becoming negligible for other matching fields. On the other hand, a periodic 2D perturbation is shown to transform the nonperiodic Bragg glass-like structure into an Abrikosov crystal with an effective Debye-Waller factor.

[Neonatal asymptomatic and childhood symptomatic hydronephrosis: Are they different nosological entities?]. / Hidronefrosis neonatal asintomática e infantil sintomática: dos entidades nosológicas diferentes?

The authors reviewed two groups of patients with ureteropelvic junction obstructión divided by age and mode of presentation: patients with neonatal asymptomatic hydronephrosis diagnosed by prenatal ultrasonography and patients with symptomatic hydronephrosis. It was assumed that in these patients we are observing a continuous spectrum of the same pathology; nevertheless, some relevant differences were found between the two groups. Diuretic renograms did not show any change in postoperative renal function among prenatally detected cases while a significative improvement followed surgery among most of symptomatic cases. A possible explanation could be found in the obstructive mechanism which was responsible of obstruction in a significative proportion of these patients. Lower polar vessels produce a progressive symptomatic hydronephrosis in an healthy kidney in respect to intrinsic obstruction which are mainly found among prenatally detected cases and which are frequently associated to congenital renal damage unresponsive to surgery.

First-order phase transition from the vortex liquid to an amorphous solid.

We present a systematic study of the topology of the vortex solid phase in superconducting Bi2Sr2CaCu2O8 samples with low doses of columnar defects. A new state of vortex matter imposed by the presence of geometrical contours associated with the random distribution of columns is found. The results show that the first-order liquid-solid transition in this vortex matter does not require a structural symmetry change.

Melting of "porous" vortex matter.

Bitter decoration and magneto-optical studies reveal that in heavy-ion irradiated superconductors, a "porous" vortex matter is formed when vortices outnumber columnar defects. In this state ordered vortex crystallites are embedded in the "pores" of a rigid matrix of vortices pinned on columnar defects. The crystallites melt through a first-order transition while the matrix remains solid. The melting temperature increases with density of columnar defects and eventually turns into a continuous transition. At high temperatures a sharp kink in the melting line is found, signaling an abrupt change from crystallite melting to melting of the rigid matrix.

[Influence of the early renal status on natural history of vesico-ureteral reflux diagnosed in the first six month of life]. / Valore predittivo dello stato renale iniziale sulla storia naturale dei reflussi vescicoureterali diagnosticati entro i primi sei mesi di vita.

INTRODUCTION: Ultrasonographic and radionuclide imaging of kidney in presence of major vesicoureteric reflux, diagnosed in the first months of life, reflects a congenital anomaly of development of ureteric bud and metanephric blastema, more than a parenchymal damage secondary to superimposed infections. These lesions are mainly observed in male infants affected by reflux and referred on the basis of a prenatal diagnosis. The impact of therapy on these kidneys is still debated. PATIENTS AND METHODS: Among 273 pediatric patients with VUR observed between 1991 and 2000, 48 cases have been selected where a reflux grade III or greater had been diagnosed within the first six months of life. Cause of admission was prenatal diagnosis in 29 cases and recurrent infection in 19. Reflux was bilateral in 30 patients. Cases of VUR associated to other urological or neurological anomalies were excluded. A complete ultrasonographic, cystographic and radionuclide study was performed in all patients included in the present study within the fourth month of life. Mean Follow up lasted 17 months. Renal damage was graded by ultrasonography and DMSA renal scan on the basis or of a reduction in total kidney size and a poor radionuclide uptake either of an altered renal profile associated to focal defects of uptake. RESULTS: Resolution of reflux within the mean follow up period, was observed in 16 patients, even with high grade VUR, whenever major renal lesions were absent or focal. When severe renal damage was initially demonstrated the expectancy of reduction or resolution of VUR was significantly reduced and surgical option was considered. CONCLUSIONS: Among patients with major VUR diagnosed in the first months of life, early renal status affects prognosis more than the severity of reflux.

The role of the renal resistive index ratio in diagnosing obstruction and in the follow-up of children with unilateral hydronephrosis.

OBJECTIVE: To assess the role of the renal resistive index ratio (RIR) in discriminating equivocal upper urinary tract dilatation in children, and thus in establishing the need for surgery, in comparison with traditional diagnostic tools. PATIENTS AND METHODS: The study comprised 40 children with unilateral hydronephrosis unrelated to vesico-ureteric reflux, posterior urethral valves, megaureter or a duplex system. In all patients one or more of the following 'indices of obstruction' were positive; an anteroposterior renal pelvic diameter of >20 mm, a half-time diuretic 'washout' (T/2) of > 20 min, a separate renal function of < 40%, and symptoms of obstruction (pain, sepsis). All these variables were measured on admission and after a mean (range) follow-up of 9 (2-24) months. After this period, all patients who were symptomatic or with two or more of the variables above the normal range were considered as obstructed and underwent a dismembered pyeloplasty. The variables were then re-assessed 6 months after surgery. The RIR was evaluated using duplex Doppler ultrasonography with a 3.5-5 MHz transducer, by the same operator. Differences between obstructive and unobstructive unilateral hydronephrosis were estimated from the mean values of the variables assessed and Student's t-test used to determine significant differences. The correlation between the T/2 and RIR before and after surgery was also evaluated. RESULTS: During follow-up the RIR was abnormal in 27 of 30 patients with hydronephrosis who were considered to be 'obstructed'. Twenty-three of these patients, selected for surgery, had a positive diuretic renogram; 11 had loss of differential renal function and 16 had recurrent clinical symptoms. There were significant differences in the mean RIR and T/2 between obstructed and unobstructed patients. Six months after dismembered pyeloplasty, the RIR returned to normal in all patients except three in whom it was previously > 1.1. The diuretic renogram, if initially showing pathology, always became normal. The RIR did not change in patients with an unchanged and severe loss of differential renal function before and after surgery. CONCLUSIONS: In this study the RIR was a good index of obstruction in children with unilateral hydronephrosis and it correlated well with the results of diuretic renography. The specificity of the RIR was reduced whenever there was severe renal damage.

[Physiologic role of the somatotrophic GH-IGF and others hormones in the domestic animals growth. Influence of the nutritional status]. / Rol fisiológico del eje somatotrófico GH-IGF y otras hormonas en el crecimiento de los animales domésticos. Influencia del estado nutricional.

In this review main hormones involved in development and muscle growth are shown with special emphasis on growth hormone (GH) and insulin-like growth factors (IGF). Chemist composition, synthesis place, action way and main action mechanisms of these hormones are reviewed. Nutritional factors which modified seric metabolites, and their effects on hormone secretion are detailed. It was observed that GH, IGF, thyroid hormones, insulin, glucocorticoids and sexual steroids act in a complex and cordinated way to produce a productive response to different> nutritional strategies.