Search

Treatments for open-angle glaucoma aim to prevent vision loss through lowering of intraocular pressure, but to our knowledge no placebo-controlled trials have assessed visual function preservation, and the observation periods of previous (unmasked) trials have typically been at least 5 years. We assessed vision preservation in patients given latanoprost compared with those given placebo.

To assess the long-term outcomes of trabeculectomy using an anterior chamber maintainer and a combination of adjustable and releasable sutures compared with trabeculectomy using a viscoelastic and solely releasable sutures.

This study aimed to investigate (1) the prevalence of nonadherence with eye drop treatment; (2) selected correlates of nonadherence at the patient and health-care organization level; and (3) the diagnostic value of the ophthalmologists' ratings, using patients' self-reports as standard.

Our paper presents the general overview of the current geophysical results, which helps to improve the geophysical image and the lithospheric structure of the Carpathian-Pannonian Basin region. Two different geophysical methods have been applied for the study of the structure and composition of the lithosphere as well as for determination of the lithospheric thermal structure. Firstly, integrated 2D modeling of gravity, geoid, topography and surface heat flow data was performed. Secondly, based on the results of the CELEBRATION 2000 seismic experiment, a large-scale 3D lithospheric gravity model was developed. The resulting map of the lithospheric thickness shows important variations in lithospheric thickness across the chain as well as along strike of the Carpathian arc. The sediment stripped gravity map is characterized by minima in the Eastern Alps and Western Carpathians. The maxima are observed in the Pannonian Back-arc Basin system, Bohemian Massif, Fore-Sudetic Monocline, Bruno-Silesian unit (BSU), Lublin Trough and partly in the Holy Cross Mts. and Malopolska unit. The Western Carpathian gravity minimum is a result of the interference of two main gravity effects. The first one comes from the low-density sediments of the Outer Western Carpathians and Carpathian Foredeep. The second one is due to the thick low-density upper and middle crust, reaching up to 25 km. The sediment stripped anomaly in the Pannonian Back-arc Basin system is characterized by gravity high that is a result of the gravity effect of the anomalously shallow Moho. The most dominant feature of the complete stripped gravity map is the abrupt change of the positive anomalies along the Pieniny Klippen Belt zone. The complete residual anomaly of the Pannonian Back-arc Basin system and the Western Carpathian orogen is characterized by a long-wavelength gravity low. The lowest values are associated with the thick low-density upper and middle crust of the Inner Western Carpathians. The European Platform is characterized by significantly denser crust with respect to the less dense crust of the microplates ALCAPA and Tisza-Dacia. That is why we suggest that the European platform represents consolidated, while the Carpathian-Pannonian Basin region un-consolidated crust.

Purpose To compare the intraocular pressure (IOP) readings taken by ICare, Pascal dynamic contour tonometer (DCT), and ocular response analyzer (ORA) with those taken by Goldmann applanation tonometer (GAT). We sought to evaluate the influence of central corneal thickness (CCT) on IOP measurements and to compare patients' preferences for the four tonometers.Methods In this prospective study, 93 eyes from 93 patients were examined. Patients were randomly divided into 4 groups to vary the order in which the tonometers were applied. CCT was measured with an ultrasound pachymeter.Results The average CCT was 558±47.4 μm. The mean ± standard deviation IOP for GAT, ICare, DCT, and ORA (Goldmann-correlated IOP) (ORAgc) were 15.1±4.8, 15.7±5.7, 18.3±5.1, and 18.3±6.6 mmHg, respectively. There was no significant difference between the mean IOP obtained with GAT and ICare (p=0.14). There was also no difference in IOP levels between the mean IOP obtained with DCT and ORA (p=0.26). There was no correlation between IOP measurements and CCT for the four instruments. Bland-Altman graphs showed disagreement between the measurements taken by GAT and the other instruments. There was no significant difference in patients' preference among the 4 instruments (p=0.48).Conclusions IOP readings from ICare were consistent with those from GAT, whereas DCT readings correspond well to ORAgc measurements. DCT and ORA readings both overestimated the GAT readings. There was no correlation between the IOP measurements and the CCT for the 4 instruments. There was no significant difference in patients' preference among the 4 instruments. (Eur J Ophthalmol 2009; 19: 783–9)

The International Glaucoma Think Tank II brought together glaucoma clinicians and researchers from all over the world to discuss current practices in glaucoma diagnosis and management, and the neurobiology of glaucoma. The meeting focused on several themes, including rates of deterioration in glaucoma patients, mechanisms of optic nerve damage, and implications for treatment. Issues such as how to measure and integrate progression information into clinical practice, screening protocols, or trials were discussed, as were promising new technologies and limitations of currently available measurement tools. Clinical applications for genetic testing were considered. Study of the neurobiology of glaucoma continues to inform our understanding of underlying degenerative processes, as well as to introduce possibilities for early detection or prevention. Many questions regarding glaucoma pathophysiology and best treatment practices remain unanswered, but with continued research and discussion, we will advance our understanding of this disease and ensure that patients receive optimal care.

Purpose To determine factors influencing color Doppler imaging (CDI) measurements, to compare retrobulbar flow velocities between patients with glaucoma and healthy controls, and to describe the correlation between CDI and ocular pulse amplitude (OPA).Methods Patients with normal tension (n=28) or primary open angle glaucoma (n=19) and healthy controls (n=22) underwent CDI and OPA measurements. Intraocular pressure, corneal thickness, blood pressure, and heart rate were also measured. Spearman correlations were used to explore relations among these variables. A regression model for repeated measures was applied to compare between diagnostic groups the flow velocity indices in the retrobulbar vessels.Results Retrobulbar diastolic blood flow velocities correlated with diastolic blood pressure and perfusion pressure (range of Spearman rho [ρ] coefficients=0.25–0.28; P=0.044–0.013 for the different vessels). Corneal thickness showed a positive correlation with systolic and diastolic flow velocities in the central retinal artery (ρ=0.29 and 0.31; P=0.017 and 0.011 for peak systolic and end diastolic velocity, respectively). Systolic and diastolic blood flow velocities were reduced in the retrobulbar vessels of patients with normal tension glaucoma (P=0.0004) as well as primary open angle glaucoma (P=0.003) compared to healthy controls. A correlation was found between OPA and the resistive index in the retrobulbar vessels of the healthy controls (range ρ=0.42–0.53; P=0.059–0.014).Conclusions Retrobulbar blood flow velocities are reduced in patients with primary open angle glaucoma and normal tension glaucoma. Blood pressure and corneal thickness may influence CDI measurements. OPA correlates with the resistive index in CDI.

This study compared the intraocular pressure (IOP)-lowering efficacy of 2 fixed combination products, brinzolamide 1timolol 0.5 suspension (Azarga, BrinzTim) and dorzolamide 2timolol 0.5 solution (DorzTim), in patients with open-angle glaucoma or ocular hypertension who required a change in therapy due to elevated IOP while receiving IOP-lowering medication.

(1) To investigate the relationship of ocular pulse amplitude (OPA) with intraocular pressure (IOP) and corneal thickness. (2) To evaluate OPA in patients with primary open angle and normal tension glaucoma (NTG).

Purpose. To compare the prevalence of side effects between eyedrops with or without preservatives, in terms of subjective symptoms and objective signs in patients with open-angle glaucoma.Methods. In a multicenter cross-sectional epidemiologic survey in four European countries, ophthalmologists in private practice enrolled 9658 nonconsecutive patients using preservative (P) or preservative-free (PF) beta-blocking eyedrops between June 1997 and December 2003. Subjective symptoms, conjunctival and palpebral signs, and superficial punctate keratitis were explored before and after a change in therapy. For statistical analysis, a χ2test was used to calculate the differences in the prevalence of symptoms and signs with or without preservatives.Results. A total of 74% of the patients used P, 12% PF, 10% a P-PF combination, and in 4% the type of medication was unknown. Each recorded symptom and all the palpebral, conjunctival, and corneal signs were significantly more frequent (p<0.0001) in the P-group than in the PF-group, such as pain or discomfort during instillation (48 vs 19%), foreign body sensation (42 vs 15%), stinging or burning (48 vs 20%), and dry eye sensation (35 vs 16%). A total of 68% of the patients had a second visit performed, of whom 63% (6083) had been evaluated on treatment difference. A significant decrease (p<0.0001) of all ocular symptoms and signs was observed in patients in whom the preserved eyedrops were diminished in number or altered into preservative free drops.Conclusions. Compared to preserved eyedrops, preservative free eyedrops are significantly less associated with ocular symptoms and signs of irritation.

Purpose This study compared the variability of intraocular pressure (IOP) measurements taken with pulse synchronized pneumotonometry (PNT) and with routine PNT (without pulse synchronization) and evaluated the agreement between PNT and Goldmann applanation tonometry (GAT).Methods In this prospective study, 148 eyes from 78 patients were enrolled. Patients were randomized into two groups. In the first group (A), the sequence of measurements was pulse synchronized PNT, routine PNT, and GAT. In the second group (B), the sequence of measurements was routine PNT, pulse synchronized PNT, and GAT. The mean of three measurements was averaged for PNT and GAT. All the measurements were performed by the same investigator, who was masked to GAT measurements. The mean IOP measurements and intrapatient standard deviations among the three tonometers were compared using analysis of variance measurement. Bland & Altman plots were used to assess the agreement between PNT and GAT.Results The variability of IOP measurements taken with pulse synchronized PNT was significantly lower than with routine PNT in both groups (1.2±0.7 vs 1.3±0.7 mmHg in group A and 1.1±0.9 vs 1.3±1.0 mmHg in group B [p<0.001], respectively). PNT measurements with and without pulse synchronization were on average ±2 mmHg higher than GAT measurements in both groups (p<0.001). The 95% limits of agreement between PNT and GAT varied between −3.8 and 8.5 mmHg.Conclusions Pulse synchronized PNT gives more reproducible measurements than routine PNT. The agreement between PNT and GAT is poor. (Eur J Ophthalmol 2007; 17: 178–82)

To evaluate the usefulness of day-long sequential office measurements of intraocular pressure (IOP) to make therapeutic decisions in patients with progressive glaucomatous damage despite apparently ‘controlled’ IOP.

Purpose To evaluate the usefulness of non-mydriatic fundus camera (NMFu-camera) and frequency doubling perimeter (FDP) for detecting glaucoma in a general population.Methods This prospective observational multicenter study consisted in screening for glaucoma in the populations of three Belgian cities. Intraocular pressure (IOP) was measured with non-contact pneumo-tonometer (NCT) and applanation tonometry (AT) if NCT IOP was ≥17 mmHg. Visual field was screened with FDP (C-20-5) and digitized optic disc photographs (ODPs) were taken with NMFu-camera. FDP was considered abnormal if at least one defective point was found. ODPs were graded as normal or glaucomatous by consensus of three glaucoma specialists. Optic disc and visual field results were matched per eye. Subjects with known ocular hypertension and/or treated primary open angle glaucoma were excluded from the analysis.Results A total of 1620 subjects were included in the study. Their mean age was 63.2 years. AT IOP was >21 mmHg in 8.2%. A total of 98.1% of ODPs could be interpreted. Glaucomatous optic discs were detected in 3.5% of the subjects. In this group only 24% had an AT IOP ≥22 mmHg. FDP was abnormal in 44.5%. The sensitivity and specificity of FDP to identify patients with an optic disc graded as glaucomatous were 58.6% and 64.3% respectively.Conclusions The combined use of the NMFu-camera and the FDP is a feasible method for an initial glaucoma mass screening. NMFu-camera may be a useful and quick method to screen for glaucomatous damage in a community. FDP in screening strategy was revealed to be not sensitive enough when setting the cut-off value at one defective test location. IOP measurements were confirmed to be a poor tool to detect glaucomatous damage.

Leaves of near isogenic barley lines containing the race-specific resistance alleles Mla1ormla1were subjected to double inoculation treatments with virulent and avirulent Blumeria graminisisolates. Attack by the avirulent isolate alone frequently caused hypersensitive death of individual Mla1epidermal cells, but underlying mesophyll cells survived. Virulent and avirulent B. graminisisolates were inoculated sequentially (inducer followed by challenger) in all possible combinations. As shown previously, where a papilla formed due to inducer attacks, the attacked epidermal cell, and to some extent its neighbours, showed highly increased resistance to challenger penetration. When epidermal cells died in response to avirulent inducer attack, adjacent cells also showed increased penetration resistance. By contrast, where the virulent inducer formed a haustorium, invaded epidermal cells, and to some extent their neighbours, showed induced penetration susceptibility to later challenger attack. Furthermore, when virulent inducer haustoria formed in Mla1epidermal cells, these cells became highly susceptible to successful infection by the avirulent isolate and vigorous colonies developed. It appears that suppressive factors released during virulent inducer infection prevented the hypersensitive epidermal cell death that normally is induced by the race-specific avirulence elicitor. However, suppression ofMla1race-specific resistance was confined to the epidermis. The presence of successful avirulent fungus infection of the epidermis often led to the death of the underlying mesophyll cells, thus generating a novel cellular response phenotype in B. graminisattacked Mla1barley.

The suppression of intragastric acidity with H2‐receptor antagonists may diminish with repeated administration. To assess the degree and dose‐dependance of this tolerance after short‐term dosing, two doses of the H2‐receptor antagonists, ranitidine (300 mg node or q.d.s.) and sufotidine (300 mg or 600 mg b.d.), were given to healthy volunteers for 1 and 2 weeks, respectively. After 1 and 7 days of dosing with ranitidine 300 mg q.d.s. the median 24‐h and night‐time pH, measured by continuous 24‐h pH‐metry, dropped from 3.7 to 2.2 and 5.8 to 3.2, respectively (P< 0.0001 for both). The decline in median pH with ranitidine 300 mg node was only significant during the night (from 4.1 to 2.9) (P< 0.04). There was little change in plasma gastrin concentrations between days 1 and 7 with either dosage. With sufotidine 300 mg b.d. and 600 mg b.d. for 1 and 14 days, the median 24‐h pH fell from 3.7 to 2.1 and from 4.6 to 2.6, respectively (P< 0.0001). The equivalent medians for the night decreased‐from 6.3 to 2.3 and from 6.6 to 3.1 (P< 0.0001). Gastrin concentrations did not change after 14 days of dosing with sufotidine 300 mg b.d., but increased significantly during dosing with sufotidine 600 mg b.d. (P< 0.001). Significant tolerance developed in 7‐14 days and it seemed to show some dose relationship. The mechanisms behind tolerance and the role of gastrin are discussed, but remain unclear.

Antisymmetric interactions with respect to spin direction give rise to spin rotations in certain perfect crystals. A new perfect crystal technique, termed Dual-Polarised-Beam technique (DPB), can be used to boost the sensitivity of the spin rotation measurements by several orders of magnitude. The typical Zeeman splitting is shown and a future experiment of neutron EDM detection with DPB using new crystals is also discussed.

Because of the stringent requirements on the magnetic precession fields this technique has taken a long implementation time. The solution of the homogeneity and of the stray-field problem is the Optimal Field Shape (OFS) which allows the use of wide and divergent neutron beams. On the ISSP thermal three-axis spectrometer equipped with OFS coils relative energy resolutions of l0−5have now been obtained. At the ILL the implementation of super conducting OFS coils is expected to yield 10−6. The quality of the spin-echo polarisation and the spin echo phase are independent of the scattering angle. A further possibility of TASSE (Three Axis Spectrometer with Spin Echo) which has been developed and is to be tested, is complete phonon focusing, that is matching of both slope and curvature of the constant spin echo phase surface to those of the dispersion surface of the excitation, the lifetime of which is to be determined.

An ultralight aircraft was used to make concurrent, near continuous measurements and to acquire spectral responses in several wavelengths over various ground features: water bodies (river and irrigation channels), geomorphological features (sand banks, levees, iron crust), aquatic vegetation (rice and spontaneous aquatic vegetation) and stubbles (millet and sorghum). The experiment was performed in Mali, along the Niger river. The airborne instrumentation made it possible to collect simultaneously spectral responses in the MSS and SPOT bands, flying height by laser rangefinder and colour video tapes of the area over-flown. Five profiles, several kilometres long, were obtained at heights above the ground varying from 20 to 75 m. Along each profile spectral data and flying height were scanned every 0-1 s and recorded on the audio channel of a videotape, after multiplexing and analogue-to-digital conversion. The preliminary data analysis suggest a very high potential for ultralight aircraft in remote sensing applications.

Temporal patterns of transcript accumulation of six host response genes (β-1,3 glucanase and five of unknown function), were determined for two near-isogenic barley lines (Algerian R and Algerian S), differing at the Ml-a locus for race-specific incompatibility with Erysiphe graminis f.sp. hordei. The cDNAs of these response genes were originally cloned in other laboratories. Transcript levels of the six response genes were measured using quantitative, radioanalytical analysis of Northern blots containing RNA isolated from leaves at discrete intervals from 0-48 h after inoculation. At each time interval, leaf tissue was also fixed and stained for light microscopic observations of fungal development and host epidermal cell responses to E. graminis. Response gene transcripts accumulated in biphasic patterns corresponding to periods of cytoplasmic aggregation and papilla deposition in host cells beneath primary germ tubes at 2-10 h after inoculation and again beneath appressoria at 10-21 h. This biphasic pattern was virtually the same in both isolines up to 21 h, indicating that transcript accumulation was a general, race nonspecific response to pathogen attack. From 21 to 40 h after inoculation, transcript levels tended to remain higher in the resistant than in the susceptible isoline, possibly as a consequence of hypersensitive epidermal cell death which was visible only by light microscopy and occurred at 18-30 h in the resistant isoline. Copyright 1993, 1999 Academic Press

Seedling and adult plant leaves of three oat genotypes, Selma, Maldwyn and OM1387 (a hybrid derived from a Selma×Maldwyn cross), were excised and treated with water or with α-amino-β-phenylpropionic acid (AOPP) to inhibit phenylalanine ammonia lyase activity, or with [[(2-hydroxyphenly)amino] sulfinyl]acid 1,1-dimethylethyl ester (OH-PAS) to inhibit cinnamyl alcohol dehydrogenase activity. None of these genotypes possess any known major gene resistance to the isolate ofErysiphe graminisf.sp.avenaewith which they were inoculated, although Maldwyn is known to possess quantitative adult plant resistance that has proved durable since 1947. All genotypes showed some adult plant resistance which limited the proportion of fungal appressoria that formed haustoria in water-treated leaves. However, this resistance was expressed more strongly in Maldwyn and OM1387 than in Selma. Treatment with AOPP or OH-PAS increased substantially the proportion of fungal appressoria that formed haustoria in adult as well as seedling leaves, indicating that phenolic compounds, probably products of the lignin biosynthetic pathway, contributed to resistance. However, AOPP-treated adult leaves remained more resistant to infection than AOPP-treated seedling leaves, suggesting that additional unknown factor(s) contributed to adult plant resistance. In all genotypes and in seedling and adult leaves, failure of appressoria to infect was correlated to the localized accumulation of autofluorescent components in host cell papillae and cell wall regions subtending appressoria. This localized autofluorescence was suppressed by AOPP treatment, and to a lesser extent by OH-PAS treatment, indicating that the fluorogens were phenolic compounds. In Maldwyn and OM1387 a proportion of host cells showed whole-cell autofluorescence, probably indicative of cell death, following attack by appressoria. Whole-cell autofluorescence was almost totally suppressed by AOPP or OH-PAS treatment, suggesting that this response was also dependent upon active synthesis of phenolic compounds. The contribution of phenolic compound synthesis to disease resistance appeared to be independent of temperature; AOPP treatment had similar effects in suppressing resistance in plants acclimated and incubated at 10 °C and at 20 °C.

The acid-inhibitory action of H2-receptor antagonists was shown to decrease after one to two weeks of dosing in healthy volunteers. This tolerance was evaluated in three randomized, placebo-controlled trials with the H2-receptor antagonists famotidine, 40 mg given after the evening meal for 28 days; ranitidine, 300 mg four times a day for seven days followed by 300 mg at night until day 28; and ranitidine, 300 mg three times a day vs 300 mg at night for 14 days. Continuous 24-hr pH monitoring with glass electrodes was performed under fed conditions. The median 24-hr pH decreased from 3.2 on day 1 with famotidine 40 mg to 1.9 on day 28 (P<0.0012). After seven days of dosing with ranitidine 300 mg four times a day the median 24-hr pH dropped from 5.0 on day 1 to 3.0 on day 7 (P<0.001) and then to 2.2 with ranitidine 300 mg at night on day 28. With ranitidine 300 mg three times a day the median 24-hr pH fell from 4.3 on day 1 to 2.4 on day 14 (P< 0.0005). With ranitidine 300 mg at night the respective pH values were 2.5 and 1.8 (P< 0.003). Tolerance to H2-receptor antagonists given in a single evening dose was only evident during the night, whereas tolerance occurred throughout the day and night with the three- and four-times-a-day regimens. A large increase in the interindividual variability of pH response was seen during the nighttime.

Patterns in the accumulation of six host response gene transcripts were determined at various time intervals, 0-48 h after inoculation of leaves with Erysiphe graminis f.sp. hordei in two near-isogenic barley lines, RISØ 5678 R (RISØ-R) (resistant) and RISØ 5678 S (RISØ-S) (susceptible), differing at the ml-o locus for resistance. At each time interval, leaf tissue was fixed and stained for light microscopy of fungal development and host epidermal cell response to E. graminis. Resistance in the recessive ml-o line was expressed by failure of fungal germlings to penetrate host epidermal cells fully and produce haustoria and was correlated with deposition of papillae at sites of attack. Transcripts of the six host response genes usually accumulated in a biphasic pattern, as determined by quantitative radioanalysis of northern blots. The initial peak of activity was observed at 4-6 h (the time of cytoplasmic aggregation and papilla deposition beneath tips of the primary germ tubes). The second peak was observed at 12 15 h (the time of cytoplasmic aggregation and papilla deposition beneath the tips of the appressoria). The time and magnitude of peaks of cytoplasmic aggregation and papilla deposition was the same in RISØ-R and RISØ-S as were patterns of response gene transcript accumulation. There were not pattern differences in transcript accumulation that could be directly attributed to differences at the Ml-o locus. The results indicate that the response genes were activated and transcribed as a general defence response to attempted penetration by the fungus because they occur in both isolines. Copyright 1995, 1999 Academic Press

Using a neutron double crystal spectrometer, thin amorphous Ni-Pd-P-samples were investi-gated at very small Q-values (10-5Å -1≦Q≦10 -3Å -1). The immersion method shows that the small angle scattering effect is mainly caused by surface scattering.

Using a novel neutron high resolution double crystal arrangement, the spontaneous shear angle which is a direct measure of the order parameter has been determined in the vicinity of the first-order ferroelectric phase transition in both undeuterated (KDP) and 90%-deuterated (DKDP) potassium dihydrogen phosphate.The temperature homogeneity of the samples was better than 10-3 K, as was the temperature control.The measurements confirm the previously reported results concerning the coexistence of both PE and FE-phases during the isothermal part of the transition. Our data differ markedly from results previously published as to the thermal hysteresis and the lowest values of the shear angle. Within the accuracy of our temperature measurement, no hysteresis could be detected. At the onset of the transition we observed shear angles of 8.2 min. of arc for KDP and 24 min. of arc for DKDP. Whilst the shear angle remains constant for BKDP throughout the isothermal regime, it varies from 8.2 to 10.4 min. of arc in the case of KDP.

Inelastic neutron spectra of B quartz were recorded at various temperatures, using triple axis neutron spectrometry. Our observations confirm the existence of a very low-lying phonon branch along the 〈1,0,0〉 directions, which exhibits a marked temperature dependence, in particular near the Brillouin zone center. This branch is very anisotropic in the (0,0,1) plane. Within the B phase a maximum of quasi elastic scattering is observed for q ≃ 0.03a*, premonitory to the appearance of satellite reflexions in the modulated phase. In addition, a transverse acoustic mode exhibits an anisotropic behaviour which is attributed to a coupling with the soft-mode. The results are consistent with a phenomenological model of the incommensurate phase transition and with a lattice dynamical model involving rigid SiO4 tetrahedra motions.

Two-dimensional kinematic modelling of extension based on the numerical solution of the heat transport equation is used to investigate the lateral evolution of lithospheric yield strength during rifting and during postrift relaxation. Two yield strength minima are shown to exist, one beneath the rift centre and the other beneath the undeformed area adjacent to the rift. These are separated by a relative maximum in the transition zone between the rift and the outer area. Initially cold (thick) lithosphere and fast extension give rise to an absolute strength minimum beneath the rift, leading to a narrow rift. On the other hand, initially hot (thin) lithosphere and slow extension lead to an absolute strength minimum beneath the rift sides, which could cause outward migration of the area of principal strain and formation of a wide rift. In contrast to some existing one-dimensional analyses, no lithospheric hardening is necessary for the formation of a wide rift and the conditions for its formation are consequently less restricted. The maximum of strength in the transition zone suggests a third mode of extension characterized by the activation of extension parallel to the rift, with undeformed areas in between. During postrift evolution, the strength of the thinned area progressively increases until the zone adjacent to the rift becomes the weakest area, inducing a widening of the rift in subsequent rifting episodes. The minimum time required for migration of deformation in successive rifting stages is termed the critical relaxation time (CRT) and is shorter for an initially hot lithosphere and low strain rate. CRT values range from few million years to more than 130 Ma for a stretching factor of 1.65. This study highlights major differences with respect to previous one-dimensional analyses when considering lateral heat transport and a progressive crustal and lithospheric thinning from the rift flanks.

The influence of silicon (Si) nutrition on resistance responses of the susceptible oat cv. Selma to attack byBlumeria graminis (Erysiphe graminis)f.sp.avenaewas investigated. Using modified Shive's hydroponic solutions, Si deprived (Si-) and Si supplied (Si+) plants were obtained. First-formed leaves were used for experimentation. Use of energy dispersive X-ray microanalysis revealed that in Si+ leaves abundant Si accumulated in leaf trichomes and at sites of epidermal cell response (halo/papilla regions) toB. graminisappressoria. By contrast, Si was barely detectable in comparable analyses from trichomes and attacked epidermal cells in Si- plants. In Si+ leaves there was a consistent but not statistically significant tendency for fewer appressoria to produce successful penetrations. Haustorium formation was unaffected by Si deprivation; however, Si deprivation was associated with a substantial increase in the frequency and intensity of localized autofluorescence responses (phenolic compound accumulation) in epidermal cells attacked by appressoria. In uninoculated Si- leaves there was an increase in the specific activity of phenylalanine ammonia lyase (PAL) compared to Si+ leaves. Enzyme specific activity was also determined 18 h after inoculation. In both Si+ and Si- leaves inoculation led to increased PAL activity, but this increased enzyme activity was far greater in the Si- treatment. It is suggested that this rise in PAL activity compensated for the lack of Si, and this compensation contributed toB. graminispenetration resistance in Si- leaves.

We underline two main characteristic properties of the incommensurate phases in biphenyl. On the one hand, the sequence of incommensurate phases is unusual, with the existence of a partial lock-in transition between a phase II with a two-dimensional modulation wave and a phase III with only a one-dimensional one. On the other hand, the specific dynamic properties of these incommensurate phases can easily be studied due to the low values of phonon damping at low temperature. The remaining incommensurability at absolute zero for the atmospheric pressure has allowed the observation of propagating phasons in phase III. Moreover, both transition temperatures tend towards the absolute zero for moderate pressure and this effect is profitable to study phasons and amplitudons in phase II under better conditions.

Spectroscopic techniques based on Larmor precession of particle spins require that for all trajectories of a diverging beam the path integral of the modulus of the magnetic field must be a constant. The amount of precession performed by each spin is then a function of the particle energy only. For cylinder magnets this homogeneity condition can be expressed as a variational problem. An analytical solution is presented for this variation problem. This solution describes the optimal field shape (OFS) to obtain the best possible homogeneity for a given magnet length. In practice the ideal shape can be obtained by superposing a series of solenoids of different lengths but the homogeneity is generally not good enough so that in-beam correction coils are needed that include corrections for the line integral differences caused by the finite-beam divergence. The solution is presented together with a method to implement it in practice using discrete in-beam current distributions. The resulting magnet has a homogeneity of 10/sup -6/, so that the Larmor precession angle is still well defined after 10/sup 4/ turns.<>